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03-30-2014, 04:55 PM | #1 |
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55 Thunderbird Gears in 39 Trans
Hey there guys,
Have any of you ever fitted 55 Thunderbird, Customline, Fairlane gears to a 39 - 48 ford Transmission? I have heard it can be done with some modification to the cluster gear shaft housing bores by enlarging bores to 7/8 from 3/4 and spline mods to the input shaft otherwise things apparently fit? Can anyone verify they have done or have seen the mods done? Regards,
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03-30-2014, 04:59 PM | #2 |
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Re: 55 Thunderbird Gears in 39 Trans
So... If it can be done, what would be the advantage?
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03-30-2014, 05:07 PM | #3 |
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Re: 55 Thunderbird Gears in 39 Trans
It gives a very similar gear ratio if not better to Lincoln Zephyr gears.
Transmission Gears and Ratios 26H Lincoln 25-tooth Low Second High 2.12 1.44 1.00 06H-56H Lincoln 26-Tooth Low Second High 2.33 1.58 1.00 Ford-Merc Lincoln 28-tooth Low Second High 2.82 1.60 1.00 Ford-Merc Lincoln 29-Tooth Low Second High 3.11 1.77 1.00 Ford Thunderbird 24-tooth Low Second High 2.32 1.48 1.00
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03-30-2014, 05:08 PM | #4 |
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Re: 55 Thunderbird Gears in 39 Trans
What Alan said.
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03-30-2014, 07:39 PM | #5 |
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Re: 55 Thunderbird Gears in 39 Trans
500,
You'll need to find the very rare output shaft that has the involute shape and correct helix to accept the first and reverse sliding gear of the later transmission. Mac VanPelt assures me that they were made at one time. This shaft allows the use of the later gear set in an early case...ala '39. The further benefit, and it is substantial, is the improved gear tooth form and the far superior roller bearing design at the junction between the input and output shaft. The later design utilizes loose rollers the fit of which is near zero flex. Charlie ny |
03-30-2014, 09:41 PM | #6 |
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Re: 55 Thunderbird Gears in 39 Trans
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03-30-2014, 09:56 PM | #7 |
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Re: 55 Thunderbird Gears in 39 Trans
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03-30-2014, 10:17 PM | #8 |
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Re: 55 Thunderbird Gears in 39 Trans
Pete, those are two excellent reasons. I like reason #2 and I saved the whole $1000 going in!
All kidding aside, I do respect that it's a big deal for some, just not for me.
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03-30-2014, 10:23 PM | #9 |
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Re: 55 Thunderbird Gears in 39 Trans
I think I would spend the bucks on a later O'drive tranny like Ol Ron suggests.
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03-30-2014, 10:32 PM | #10 |
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Re: 55 Thunderbird Gears in 39 Trans
B-O-B, I don't think an overdrive would satisfy that itch.
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03-31-2014, 12:36 AM | #11 |
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Re: 55 Thunderbird Gears in 39 Trans
Really Keen on any further info on this, would like to give it a go. I have heard of one being completed here but lost in history is what gears from what trans were used.
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03-31-2014, 01:56 AM | #12 | |
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Re: 55 Thunderbird Gears in 39 Trans
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03-31-2014, 03:46 AM | #13 |
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Re: 55 Thunderbird Gears in 39 Trans
Gota say, the stronger gears won't stop the gearbox case blowing open and leaving the lay shaft on the asphalt under the car. It's a cool thing, having the better ratios in there, especially with the appropriate rear end gears. And using Tbird stuff to do it, is cool. But I feel the trans case is not strong enough to make use of all this stuff. The yards arnt still full of early Ford parts, so this has to be thunk about.
A nice 4 speed top loader with good close ratio set and converted to fit to the torque tube, would be many times better. Maybe even a T5 done the same (seen a pick of this somewhere) but get those pointless S10 gears out, and put a close ratio set in. Martin. |
03-31-2014, 06:01 AM | #14 |
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Re: 55 Thunderbird Gears in 39 Trans
Are the parts available? What does a scrounger need to be looking for?
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03-31-2014, 06:38 AM | #15 |
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Re: 55 Thunderbird Gears in 39 Trans
TT,
I guess a big swap meet is where I'd look. When we go to Canfield or Hershey I always carry a late 1st/rev sliding gear and if I see an output shaft I try the gear on it. A late slider will bind on an early shaft. At a glance, even side by side it would be tough see the difference. I'll bet Bob Drake could make that shaft.......... Charlie ny |
03-31-2014, 07:58 AM | #16 | |
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Re: 55 Thunderbird Gears in 39 Trans
Quote:
Useless S-10 gears? Not sure what you mean. There were a bunch of different versions of this trans and they had different ratios. Some are better than others, but that 5th OD is a blessing for a flathead. |
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03-31-2014, 11:57 AM | #17 |
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Re: 55 Thunderbird Gears in 39 Trans
S10 t5's often come with a 4.03:1 first gear. Pretty useless behind a flathead. Then yawning gap to second. Good for a rubbish engined pickup. Flathead trans commonly use a 2.8 or 3.1:1 first gear. And most can pull away from stop in second which is about 1.6:1. Compare this with the 4.03:1. Their are as you say lots of different applications for the t5, with lots of different ratio sets in them. Often the s10 with a good gear shifter location has the useless gears I speak off. If you were to use a gear set out of say a V8 engined mustang or such with a 2.95:1 first gear, we're talking a completely different driving experience. That 2.95.:1 will pull like a stocker from a stop in first pretty much the same as the three speed, and have closer ratios through the trans and the fifth gear everybody seem to think they need.
This Is what I mean when I say useless gears. If your gonna go through all the stuff necessary to get this t5 in your Ford, why not put one in with appropriate ratios? Martin. |
03-31-2014, 12:37 PM | #18 |
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Re: 55 Thunderbird Gears in 39 Trans
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03-31-2014, 05:28 PM | #19 |
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Re: 55 Thunderbird Gears in 39 Trans
Thanks for the T5 info, but not what I am interested in, I like the idea of retaining the 3 speed.
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03-31-2014, 05:34 PM | #20 |
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Re: 55 Thunderbird Gears in 39 Trans
In 1951 FoMoCo went to the new design sometimes refered to a diamond shaped gear sets. All of these transmissions had the long main output shaft. If a fellow had the wherewithall it might be possible to cut the shaft down & add splines for the U-joint. FoMoCo or Borg Warner might have made a shaft for this so that replacement gears could be limited to the new design so they could discontinue the old style. Mac VanPelt would sure be the one who knows this stuff.
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03-31-2014, 06:50 PM | #21 |
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Re: 55 Thunderbird Gears in 39 Trans
Last year we purchased a pickup truck load of used and NOS Ford trans parts from some nice guys in western Michigan. After getting home and sorting thru everything, I set the 51a-7061 mainshafts in the bin. When I went to use one a few weeks later, I couldn't get the 01A-7100 low/rev gear to slide on. I've been down that road before so I grabbed a 1A-7100 gear and tested the fit on the splines....perfect! In all other respects the main shaft was identical to an ordinary 51A-7061 closed drive shaft.
There was no box. There was no marking of any kind on the shaft. I finished the job with a regular 51a shaft but put the oddball aside. I did a test fit to assemble this shaft in a normal 78 case with 81A shifter assy. Used the 51-54 cluster gear (1A-7113) plus the 28 tooth 1A-7100 slider, a 1A-7141 rev idler, the 1A-7102 second gear, and a 1C-7017 main drive gear, and the usual 8M-7124 synchro assy. In other words I built a "39 style" closed drive trans using the 51-54 gears. It fit and worked perfectly. Ended up building two trannies for customers who wanted the slightly higher gear ratios this delivered, and sold the combo of gear to another customer who built it itself. I scoured ALL my gear catalogs and could not find any reference to this shaft. To this day I still wonder who made them. I'd love to come up with a few more.
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03-31-2014, 07:20 PM | #22 |
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Re: 55 Thunderbird Gears in 39 Trans
One place that MIGHT give an origin for the oddball shaft...
Don Francisco, HRM tech guru long ago, did a tech on use of Lincoln Zephyr gears somewhere around 1956. At the time LZ gears sets were offered by the speed equipment industry for the various later transmissions with all sorts of special hardware like small type input shafts. This stuff was offered in kits of increasing complexity and price into '54-55...perhaps the odd shaft was a speed equipment offering and not from any OEM application, like the small input gears. The article was published in several formats in Petersen books and Car Craft, but I believe the most detail was in the HRM article. |
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03-31-2014, 07:26 PM | #23 |
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Re: 55 Thunderbird Gears in 39 Trans
On that SM article...Zephyr gears are HIGHER and so offer less torque multiplication than For 28 or 29. Ford used them in the Lincolns with 4.44 gears to get that torque back up, adding a 30% overdrive to avoid killing the cruising speed.
Used alone with normal rear gears in a 3,000 pound car with a mild flathead, I would expect them to slow down acceleration under most circumstances. I think successful uses were in light roadsters with big strokers and stiff gearing. The most extreme ones, the 25 tooth, are starting to approach a 4 speed trans with first gear missing. I think for most people with mild engines and full bodied cars, the 28 tooth Ford set is likely superior. |
03-31-2014, 09:11 PM | #24 |
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Re: 55 Thunderbird Gears in 39 Trans
If you read the last paragraph in that old article, you will note that the t-Bird gears' ratio is nearly identical to the 26T LZ gears. I'll grant that the 55 Bird gears are a bit stouter than the LZ gears, but you don't have to line bore the case to make them fit the gearbox. Plus (and I am not in my office to check this right now) I think the Bird input shaft is longer than the Ford or LZ input shaft....requiring some remachining of the shaft to shorten and extend the clutch hub splines to the rear.
No question that a fire breathing hemi will most likely chew up the modest Ford gearbox and spit it out in hot oily pieces. Probably a better idea to figure out another transmission that is beefy in every component. The comments about using the LZ gears or any other high (close ratio) gears are spot on when taking into consideration the weight and power of the vehicle. These will not necessarily deliver the kind of performance the driver was hoping for. Allow me to step back up on my soapbox once more for a moment. We all drive late model cars (even if not as your daily driver). What happens when you climb in behind the wheel of that old flathead Ford? For a few minutes or hours, you are your father....or your grandfather.....just driving the cool old car as they did. It's a time machine with all it's unique quirks, it's special sounds, and the smell of warm oil slowly burning off that drip on the engine. So the trans isn't fully synchronized? So it has only three forward speeds? Learn to love it for what it was....and is now. Pull your fedora down over your brow and head on down the road....
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03-31-2014, 09:47 PM | #25 | |
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Re: 55 Thunderbird Gears in 39 Trans
Quote:
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04-01-2014, 01:53 AM | #26 |
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Re: 55 Thunderbird Gears in 39 Trans
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Thanks Mac, I get all the above, that's why I want to retain the 3 speed and not cop out for a t5, but I also like to push the boundaries and get the best result and most enjoyment you can whilst out on the road, and the idea of tinkering and stepping outside the square for that is why I am curious. Sure its easy to mail order a set of Repo zephyr gears, but that's hardly a challenge is it! Thanks again. JG
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04-01-2014, 05:16 AM | #27 |
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Re: 55 Thunderbird Gears in 39 Trans
I understand the curious tinkering. I've done plenty of that with our old Ford trannies.
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04-01-2014, 11:33 AM | #28 |
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Re: 55 Thunderbird Gears in 39 Trans
While were talking about different gears in early Ford transmissions, probably one for Mac. 1949-51 Merc overdrive trans. (the ones with the small bell like 32-48 trans. Do these gears n stuff work on the post 1939 main shaft? Just out of curiosity really, or do these have a different helix on the main shaft, been told there different at some point but would like to know for sure.
Thanks in advance, Martin. |
04-01-2014, 12:27 PM | #29 |
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Re: 55 Thunderbird Gears in 39 Trans
I'm fairly well versed in the 49 thru early 51 Merc cogboxes and they used the same intermediate gear and low/reverse slider as the earlier Ford 3-speeds 51A and 21C prefixes respectively. Just the main output shaft & case was different and there were the two types. Trans with overdrive and trans without.
It's the later 51 and on stuff that is all different with respect to Ford & Mercury to early 3-speeds. |
04-01-2014, 05:25 PM | #30 |
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Re: 55 Thunderbird Gears in 39 Trans
Cheers for that Mr wrench.
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04-01-2014, 05:55 PM | #31 |
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Re: 55 Thunderbird Gears in 39 Trans
For the 49-54 crowed, why not the T-85 with OD. It's abolt in, don't even have to open the case.
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04-01-2014, 09:46 PM | #32 |
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Re: 55 Thunderbird Gears in 39 Trans
I think the goal with this thread is to try and get the most (strength, performance and effective gearing) out of the old 39 3-speed to maintain the early Ford closed drive rear end.
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04-01-2014, 10:27 PM | #33 | |
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Re: 55 Thunderbird Gears in 39 Trans
Quote:
About the T-Bird gears/'39 trans mods. I understood Jim's thoughts. Jim had NOS '56 T-Bird, 3-speed gearsets. I said "lets do it". I am driving this sweet trans in my "orphan looking", 21-stud '35 Ford, 5 w. rumble seat coupe. I don't feel free in talking about the machine work , parts numbers, or specific measurements. That info is Jim's, not mine. Nationwide, people know Jim. For those that are interested, he is currently featured in The Rodder's Journal "Scrapbook". Go to Chapter #10, pages 178-197. Read about the experiences of Jim Perkins, Homer Ward, and Art Maimbourg. All are still with us, representing a wealth of Early V-8 Ford knowledge, that we should be lucky to have ourselves. Steve Crain Last edited by scrain; 04-03-2014 at 11:40 PM. Reason: spelling |
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04-02-2014, 03:54 AM | #34 |
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Re: 55 Thunderbird Gears in 39 Trans
Yes sir!
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04-02-2014, 03:58 AM | #35 | |
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Re: 55 Thunderbird Gears in 39 Trans
Quote:
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04-02-2014, 11:38 AM | #36 |
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Re: 55 Thunderbird Gears in 39 Trans
[QUOTE=Mac VP;85136
Allow me to step back up on my soapbox once more for a moment. We all drive late model cars (even if not as your daily driver). What happens when you climb in behind the wheel of that old flathead Ford? For a few minutes or hours, you are your father....or your grandfather.....just driving the cool old car as they did. It's a time machine with all it's unique quirks, it's special sounds, and the smell of warm oil slowly burning off that drip on the engine. So the trans isn't fully synchronized? So it has only three forward speeds? Learn to love it for what it was....and is now. Pull your fedora down over your brow and head on down the road....[/QUOTE] Mac You nailed it. My Mantra |
04-02-2014, 01:45 PM | #37 |
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Re: 55 Thunderbird Gears in 39 Trans
To date all I have is this article an at least three peoples say so that they have done it, some have used 56 Thunderbird gear sets, the article states 55 T Bird gear set. I have procured a set of the article stated part numbered gears so will see how it looks on arrival. Watch this space,
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04-11-2014, 04:51 PM | #38 |
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Re: 55 Thunderbird Gears in 39 Trans
Well the first the 55 Thunderbird gears arrived today and dimensionally it looks good, fits the case etc, eagerly awaiting some more to arrive from stateside to see how this is going to fly!
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04-19-2014, 11:08 PM | #39 |
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Re: 55 Thunderbird Gears in 39 Trans
So far the input and cluster have arrived and both fit in there respective positions ok, the input will need shorted to suit but that is no biggie. The gears are definitely "stouter" looking than the 39 style gear set. I was hoping to have everything to have a play around over the Easter break, but no go.
Still appreciate any info from anyone who has achieved this or has a transmission equipped with these gear sets. JG
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07-31-2014, 03:32 AM | #40 |
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Re: 55 Thunderbird Gears in 39 Trans
Pretty much have everything for this project now bar awaiting some Thunderbird bearings. Loosely assembled in the case its interesting just how close the gear sets are. Different for sure but this project is not as technical as I first thought. I have found a machine shop that specialises in gear cutting and the guy tells me he has done one before awhile back for a guy, so nothing new here!
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07-31-2014, 03:55 AM | #41 |
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Re: 55 Thunderbird Gears in 39 Trans
Not many responses, but I for one am following with interest.
Keep up the good work on this interesting job. Mart. |
07-31-2014, 06:17 AM | #42 |
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Re: 55 Thunderbird Gears in 39 Trans
I think the 55 t bird trans is the same as 55 mercury is the same thing.
I would guess it may work with open drive. Those gears were very tuff. If it was easy it would be done today. I would like to see it work. |
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07-31-2014, 08:15 AM | #43 |
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Re: 55 Thunderbird Gears in 39 Trans
Reading this post made me think abour what i did to my 46 way back, 1&r were missing teeth, and I couldn't find any gears, i found a later model trans missing the input shaft and the gears looked much the same ---except the cluster had 1 less tooth ---i put it together anyway, it didn't make noise, and survived side steeping the clutch downshifts many times ---the countershaft bearings were all loose needles, not the caged ones the original trans had, I remember doing something to the thrust washers too ---I never found out what the trans was from, but the case was much different than the 46, and looked different than the 49-50 flathead trans pictures
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02-25-2021, 03:28 PM | #44 | |
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Re: 55 Thunderbird Gears in 39 Trans
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You mean like this one we did on a '35? 2.95 Camaro gear set! 4.03 is for the 'uninformed'! DD |
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02-25-2021, 10:41 PM | #45 |
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Re: 55 Thunderbird Gears in 39 Trans
I'll see if Lawrie says something, Im sure he modifies for later gears to fit.
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02-26-2021, 01:49 AM | #46 |
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Re: 55 Thunderbird Gears in 39 Trans
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