Swap 46 transmission internals into a 37 box

[36coupe]

My 37 3 speed has a couple chipped teeth. If it was all I had I would probably run it as is.
I have a real clean 46 3 speed side shift transmission. I wanted to confirm that I can swap the 46 gear set into the 37. I was told it would be a better shifting upgrade. I’m on a bit of a budget but what parts should be considered consumables and what to look out for when tearing down the transmissions?
All I have right now is a gasket set new for the 37.
Thanks

[40cpe]

I can't help you with the fine points of the inspection, but I'm pretty sure you will need to change the second/high shift fork to one with a 3" fork unless you already have the later gears in the '37 transmission.

[36coupe]

Okay thanks

[Zeke3]

You should get a copy of Mac Van Pelt's transmission overhaul book, it will take you through part identification and a complete overhaul of the transmission.

[Karl Wolf]

Originally Posted by 40cpe

I can't help you with the fine points of the inspection, but I'm pretty sure you will need to change the second/high shift fork to one with a 3" fork unless you already have the later gears in the '37 transmission.

One better, get a top from the later box that is the one the 3" fork comes from.
1939, or the truck 3 speed- to 1948. (I think?)
If you put the 3" for in the earlier lid, you'll have to reposition it- on the shaft- drill a new hole in the shaft the fork goes on.
Takes some care... Getting the fork in the right position. Drilling through the shaft.

Don't try to use the earlier fork

Karl

[36coupe]

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Originally Posted by Karl Wolf

One better, get a top from the later box that is the one the 3" fork comes from.
1939, or the truck 3 speed- to 1948. (I think?)
If you put the 3" for in the earlier lid, you'll have to reposition it- on the shaft- drill a new hole in the shaft the fork goes on.
Takes some care... Getting the fork in the right position. Drilling through the shaft.

Don't try to use the earlier fork

Karl

I do have a 46 truck box along with the 46 side shift . It almost seems a shame to rob 2 transmissions to modify my 37.

[Juergen]

If you really have a 37 transmission, the synchro looks like a donut with a slot in the center. The side shifters have the later synchro which looks like a hockey puck with a slot towards its rear. Only the cluster, 1st/reverse and reverse idler gears are the same if the cluster tooth count for both trans is the same. So just use the side shifter's parts exclusively. The later fork is not just 3 inches wider but is the fork is located 1/4 inch further back with its mounting hole at the same location as the earlier fork. No drilling is required but the fork must have a 91A-number on it or it won't work; moving the fork position puts the neutral slots for both forks in different locations. Unless the trans is "like new", replacing all the bearings, synchros, thrust washers and seals is recomended as per van Pelt's book

[Hal Beatty]

And you may have clearance issues under the cluster gear causing problems installing the main drive gear... but that is fixable.