The Stovebolt Site Forums The Shop Area Driveline T85N Transmission

I have a 49 Chevy 3100 with a 12/63 dated 235ci engine. Original 3 speed column shift trans, torque tube and diff. I understand that converting to a T85N trans with open drive shaft and updated rear end is a very good option.

Several questions:

1. Is the T85N the same as a T85?
2. Would a non GM transmission fit right in with the 235 or are input and output shafts the same?
3. I understand that a T85N was the truck version of the 3 speed with overdrive, but is a 3 speed with overdrive from a GM mid to late 50's car the same thing? Would it work? Installation the same?
4. With the T85N does the shift linkage, input shafts, bell housing, etc all stay the same?
5. Anyone know the transmission serial numbers for the T85N?

I don't want to purchase something only to find it won't work!

Thanks for any input.

The T85 and T85N are mostly Ford and Jeep application, the bolt pattern will not be correct. The only GM application for that trans that I know of was in some Pontiac Tempest models, listed as the "Dearborn" transmission, and they used a special bellhousing for that. A much better choice would be to find an SM319 from a '55-'66 car or truck. It will bolt right up to your existing bellhousing, though you may need to swap the side cover for it to work with the stock linkage, depending on what year and vehicle it came from. The SM319 is the same main transmission as the SM318, but with the R10 overdrive. The overdrive unit, except for the adapter, is the same as the one found on the T85N.

Well it seems I got that messed up. Thanks for straightening me out.

If I need to swap the side cover do I swap it with the cover from original trans? It'll fit?

Again thanks.

The side cover from your original transmission will fit the SM319 just fine. If you can find one from either a '55 1rst or 6 cylinder '55 2nd, the entire trans should be a direct bolt in without having to alter the linkage or do a side cover swap.

The heavy duty option for a 3 speed in a GMC 1955 and up was called a SM320. It was actually a T85 Warner and shares a lot of parts with the Ford version of the T85. Apparently not many GMCs were ordered with the heavy duty option because there are not many of them around. They were a very tough transmission. It is characterized by a 9 bolt shift cover.

I forgot about the HD 3 speed option, it was offered in the Chevrolet as well. But as far as I know, it was never offered in the GM bolt pattern with the overdrive.

Thanks again.