The Stovebolt Site Forums The Shop Area Driveline 1948 3100 4 speed original to truck?

I have a 1948 3100 5-window. It has 216 and the SM420 4-speed. The serial numbers on the Transmission shows it as a 1948 and would be correct for this model truck if it was ordered that way. The Truck DOES have some parts for column shifter attached to the column. It does NOT have the shifter itself but only the "ROD" that passes through the firewall down toward gear box bottom and the other part at base of column that the shifting linkage would attach to. NO OTHER parts are present. The sm420 is a top shifting transmission with a floor shifter and no need for the column shifter of the 3 speed.

I think that this transmission probably replaced a 3-speed with column shifter at one time in its life. I dont think there is any way of ever knowing but would the presence of some column shifter hardware be enough to confirm that or was it possible that all trucks on the assembly lines got some parts installed before it took a left turn on the line and got the optional 4-speed.

I think that 1948 was first year of this Trans option so maybe this could be the case???

Any input would be appreciated

Just wondering if this transmission could be the original with this truck.
Thx!

SM420 #

sm420

Two possibilities. One, the column has been changed at some point. Two, the transmission has been swapped. It would not have come with parts for both systems from the factory.🛠

Sound like came w/ 3spd, was changed to 4 speed. That's how my '60 was when we got it in '73.

Yes. I am gonna go back to the 3 speed with column shifter. I will keep the 4 speed as well. I would like to have a 3 on the tree for my kids to learn as a piece of American History that I doubt will ever make a come back.

Does the hole for the shifter in the floor transmission cover look like a factory cutout?

The floor section that the transmission comes thru the floor was missing when I got the truck. PO had just put some sheet metal in its place. I am sure at this point that the 4 speed was installed after the fact.
The u-joint that attached inside the torque ball is def not original, some kind I never seen before. No bolts to disconnect the collars. Had to slip the the cups off to remove it from the yolk.
The BellCrank is still in place on the bellhousing and is only used on the 3 speed. I would say that reviewing all the evidence it was originally equipped with a 3 speed and column shift.
Thanks for the replies

Hello all, Mike here. I decided that I had to have a 1948 GMC/Chevy. Now I have One.
It has 124.5 wheel base, 6 lug hubs, question how do I know for sure if it is 3/4 ton or 1/2 ton? Thank you for sharing.
Old Mike.