M35A2 Transmission Swaps

[Hummer Guy]

I know this been talked about a lot, but I haven't seen that many actual swaps with the m35a2 trans other than the Alison AT545 and the same Spicer. Has anyone swapped any other transmission in the m35a2 with a longer overdrive? I was thinking about the NV4500 since its close to the same size of the 3053a, but it will need some modifications to handle the weight of the M35a2 since its only designed for 14,500 GWR. What other transmissions is there to fit? Preferably a manual but I'm open to hear what autos would fit as well. Also, if you swapped something different, what did you swap and what modifications did you have to do?

The main reason I'm looking into this is because I have 2 leaks coming from my spicer and I'm tired of the 1st to 2nd shift.

 

[Jeepsinker]

Anything with an SAE3 bellhousing will bolt up, but finding another suitable standard transmission with a higher ratio final drive that will actually fit in the truck is the hard part.

 

[4XDesign]

Eaton FSO family would work. FS versions are abundant but the O overdrive versions are expensive and no easy to find. I searched for one for my c60 rollback. I did a Cummins swap. I never found one for a deal and I ended up using a 10 speed overdrive and got her in there.

 

[Hummer Guy]

Hmm, I wonder how the 7 speed spicer would fit, I believe it has a 0.73 overdrive. There's one that's for sale currently close by me

It has a SAE 1 but I'm sure there's adapters

 

[Trango]

When I put a 3208 in the deuce in my first swap, I put in a 6855 with (as I recall) a .69 OD. There are a few challenges with swaps in that platform:
- the tcase position means that any trans that goes in needs to be short or you move the transfer case back, which is tough because of systems like the ebrake etc.
- you run out of splits. 5 forward gears, even with a high revving engine, is limiting, especially on hills. You need to practically redline the engine only to almost lug it again when you upshift. This gets worse with a wider gear range. There is a reason most OTR/CMV trucks have at the very least 9 speeds and sometimes up to 18.
-BHSG, but that can be solved.

IMO, don't touch the trans until you swap the engine. Then, choose a better trans. My current build has a 13 speed - it's so great.