The Stovebolt Site Forums The Shop Area Engine Shop Transmission to inline six

I am interested in finding out which manul transmissions match up to my in-line six cylinder. I have a 46 Chevy 2 ton truck that needs to have the tranny rebuilt or replaced. The current one seems to be one that was built for Army trucks. I cannot seem to find any information on it yet. Seems to be a T-33 but I am not sure. Does anybody have any experience with these transmissions? Where I could get parts for it? What transmissions I might consider replacing it with? Any help is appreciated.

The SM420 is good if you want a 4 speed. It was used in 2 ton trucks from 1948-1960 something. I have one that came from the factory in my '50 half ton.

Thanks for the info. Will get out the word as to what I need. I did find out that the tranny that is in my 46 is from a GMC 6x6.

Is your tranny the 4 speed automatic? Also, if a sm420 fits so will a sm465, newer model with reverse to the right and down. '67 and later, iirc

I don't think the Military allowed automatics in their trucks back in the early days.

GMC did indeed use an automatic transmission in their WWII G508 6x6 model and was refered to as a Hydromatic. You can buy replacements for under $300.00 at Sam Winer Motors, Akron Oh. e-mail [email protected] (no website). GMC also used a Spicer 5spd od model 3053A in their G749 series 6x6s. I believe the Hydromatics bolted behind the 302. I'm not sure which engine was used in the G749. www.boyceequipment.com and www.adelmans.com are both good sources for military and other truck parts.

I didn't realize they used them in WW2. Had some in 6x6's for fire trucks, Korean war vintage. 4 speed hydramatic with a built in hi/lo range. You could also switch the shift points between conventional shift and max rpm shift. Considering the time, they were a good tranny. by today's standards, they leave a lot to be desired.

The tranny is a five speed. 4th speed is 1:1 ratio and 5th is overdrive. I found some numbers on it, T-93, maybe now I can find some parts to it. I am trying to get some bearings for it and some of the gears need replacing. Anybody got any other suggestions where I may find some parts for this ole but grand beast?

Joe,

I have a trannie that I've been trying to id. I've suspected that it was a 4spd from a 40-47 GM truck. A few others have suggested the same to me, including someone on this board. I bought it from a guy, sight unseen, who told me it was an SM420. Once I tore it apart, I learned that it was NOT an SM420. He has offered to buy it back, but if your interested in it, let me know. Its been completely cleaned - wirewheeled and powerwashed and all the internals have been cleaned. I plan on reassembling it, without gaskets and using the bearings that came in it, and sending it back, but if you can use it, I'd be willing to work something out!

Let me know!

Fred T, The hydromatic transmission was used in the G749 GMC 6x6, this would be a Korean War era vehicle. The Spicer 3053A 5sp od was supposedly used in the G508/CCKW GMC (WWII) and according to Boyce equip in Ogden Utah holds the world speed record for manual transmissions. Just a clarification, thanks for pointing out the mistake.