The Stovebolt Site Forums The Shop Area Driveline 1956 4sp driveshaft

Anybody know what years driveshaft fit the 56 3100 1/2 ton SWB truck with the SM420 transmission. . Looks like the SM420 transmission used to about 1967. Or is there a better way to get to a 4speed and floor shift trans, other than the SM420.
Truck already has a 283 with a later 3speed and cobbled up shift linkage. Column shift not an option. as it has been replaced.
Thanks
Charles

If you're not worried about originality....all kinds of things you could do.

SM420 is a 4 speed that's effectively 3. Granny low is useless for most of us.

Are you keeping the 283?

"SM420 is a 4 speed that's effectively 3. Granny low is useless for most of us."

Correct, unless you swap the 1/2 ton 3.90 R&P to a 3.38?

Yes, plan on keeping the 283 for now, eventually may go to a 350, but for now the 283 is just fine. Just looking for the most economical way to get to a decent floor shift that is more user friendly than what's there now. Possibly a std 4 speed as seem to be shifter kits for them, but don't know how well they work in a PU for ergonomics. Originality not an issue, take to much to make it original. Originally an Army truck and that Army olive green a real pain to remove . That is some tough paint

Passenger car 4 speed shift linkage mounts on the very rear housing of the transmission. That makes it very close to the stock seat.
Most 3 speed conversions have the same problem. Some on this site have car 4 speeds, perhaps they can give some guidance.
It's not easy or cheap to fix "modifications".
Fred

I have a '56 3100 with a SBC with a Saginaw 4-speed that has a T&F Shifter.

http://www.hotrodscustomstuff.com/OLD_SITE/TFshifter.html

I really like it!

Mike B

Mike,
That's a real shifter!
I believe that Deve has designed something very similar for use with a 3 speed OD trans.
From my experience with aftermarket 3 speed floor shift conversions, many are sloppy new.
Finding a used one that isn't worn out is a real challenge.
Fred

The SM420 would be a very easy conversion because it will bolt right up to the housing and factory floor pans are readily available to replace the three speed floor pan that your truck has.

There are two versions of the four speed floor pans for TF trucks. One was used on the 1/2 tons and just has the cut-out for the shifter. The other one was used on the 3/4 ton and larger trucks. It has the cut-out for the shifter and a second cut-out for the ebrake lever that was attached to the tranny on the larger trucks.

The 1/2 ton SM420's have a different rear yoke than the ones for the larger trucks that had the ebrake assembly.

So the easiest way to do a four speed for you, if you have still have the stock rear end, would be to find an SM420, drive shaft and floor pan out of a 55.2 to 59 1/2 ton SWB. Everything will bolt right in. 1960 to 1966 SWB four speed driveshaft would probably also work.

Matt