The Ford Barn - View Single Post - 1955 t-bird 4.10 gears to replace 3.31

miker98038 · 12-22-2019, 08:57 PM

If you're asking if the 4.11 gears will fit in the 3.31 housing, best I know the answer is yes. I know it'll work the other way, and best I can recall the rear cover gasket was the same on my 3.31 rear ended as it was on the 4.27 I bought to replace it. You will need the correct carrier for the 4.11's, as rotorwrench points out.

As to what you have, there's also a difference in the axle and bearing sizes between various units used by Ford in the same time frame. Bird, wagon, police units, and trucks, may or may not have been different. Worse, opinions and experiences seem to vary on this. So you'll need to look. Randy's can help with that I think.

A word of advice based on experience. Changing the gears is time consuming, even if you pull the rear end out of the vehicle. Expensive if you have to hire it out. With a 351 and a C4 in a bird, you're going to want some form of limited slip, and that's more money. You may also find the housing and tubes are warped or leaking. Been there and done that, too. Much easier if you can pull the center section, and have 2 if needed.

If I were doing this again, I'd find a more modern rear end as Ole Don suggested. I could have a custom 9" in my bird for the money I've spent screwing with the 44 over the years from engine and transmission changes and needing to change ratios. Not to mention the better brakes using more available parts.

12-22-2019, 08:57 PM	#7
miker98038 Senior Member Join Date: Mar 2013 Location: Kent, WA. Tucson, AZ Posts: 1,398	Re: 1955 t-bird 4.10 gears to replace 3.31 If you're asking if the 4.11 gears will fit in the 3.31 housing, best I know the answer is yes. I know it'll work the other way, and best I can recall the rear cover gasket was the same on my 3.31 rear ended as it was on the 4.27 I bought to replace it. You will need the correct carrier for the 4.11's, as rotorwrench points out. As to what you have, there's also a difference in the axle and bearing sizes between various units used by Ford in the same time frame. Bird, wagon, police units, and trucks, may or may not have been different. Worse, opinions and experiences seem to vary on this. So you'll need to look. Randy's can help with that I think. A word of advice based on experience. Changing the gears is time consuming, even if you pull the rear end out of the vehicle. Expensive if you have to hire it out. With a 351 and a C4 in a bird, you're going to want some form of limited slip, and that's more money. You may also find the housing and tubes are warped or leaking. Been there and done that, too. Much easier if you can pull the center section, and have 2 if needed. If I were doing this again, I'd find a more modern rear end as Ole Don suggested. I could have a custom 9" in my bird for the money I've spent screwing with the 44 over the years from engine and transmission changes and needing to change ratios. Not to mention the better brakes using more available parts. Last edited by miker98038; 12-22-2019 at 09:15 PM.