The Stovebolt Site Forums The Shop Area Driveline What transmission?!? 1950 1/2-ton w/ 1955 261

Hi all,

So I picked up this 1950 1/2-ton pickup a month or so ago, it had a seized 1954 235 in it that I'm going to pull and replace with this 1955 261 that I just found with the help of fellow Stovebolter cmayna. The truck still has the original 3-speed on the column, torque tube and rear end. I want to change out the transmission for a floor shifter but keep the torque tube and rear end for the sake of originality (for now) -- I know I'll be left with a low top speed but don't mind keeping her to the back roads. I'm also a grad student and don't have a ton of money or the skill/experience to do anything too far out or expensive - I'm thinking relatively simple (bolt-on), cheap, and reliable, even at the expense of performance... within reason, of course.

So considering my setup and priorities, what is my best transmission option? Seems from reading up on the web and SB forums like there are two main options for somebody like me:

1) find an original 4-speed from an AD 1/2-ton truck like mine and be happy starting in 2nd gear (ok with me... not good, just ok), or

2) find a Saganaw 4-speed and buy the $400 installation kit from Patrick's. I know Patrick's recommends M&R rebuilt Saganaws for this purpose, but they're $900 -- pretty steep for me, although I assume with some searching I could probably find a decent working Saganaw for less (??)

Other options I should consider? Any help will be greatly appreciated.

That would cost you less than buying the Patrick's adapter and a transmission. You'll need an SM420 4-speed with the torque-tube adapter/receiver on the rear, and a suitable u-joint. These show up often in the Swap Meet.

Awesome, thanks Tim. Any chance I already have either the adapter or the u-joint, considering the seized 235 that's in the truck now?

Also, in order to bolt up to my 261, do I need to look for an SM420 from a particular era or with a particular feature? (# of splines, etc.)
Thanks, N

"Any chance I already have either the adapter or the u-joint, considering the seized 235 that's in the truck now?"

3-speed u-joint and 4-speed u-joint are different (you need the 4-speed forward yoke and the 3-speed rear yoke).

The torque-tube adapter (rear cover) on the rear of the SM420 is an SM420 specific part.


Also, in order to bolt up to my 261, do I need to look for an SM420 from a particular era or with a particular feature? (# of splines, etc.)

Wait to hear from others on this one. I think that any year SM420 will work.

You would use the clutch housing and clutch assembly (including throw out bearing) from your 1950. Use a new pilot bushing in the rear on the driveshaft.


Your speedometer will be off unless the transmission has the drive and driven speedometer gears for a 4.11 rear end (try to buy a set in the Swap Meet).

Other options I should consider?



You might consider using the 3 speed and column shift, since you've already got it. You might end up liking it. Run it while
you're looking for a four speed. You'll save a little money also.
In any event...good luck with your project.

Tim, thanks a lot for your input - it's much appreciated.

Steve, I'm definitely considering keeping the 3-speed for a time. I just figured since I was going to have to change a lot of parts while putting in the new engine, I might as well just upgrade the transmission as well. But you're right, maybe it's better to put off a while. I guess it will just depend on my ability to find a four-speed while everything comes together. Thanks!

Well, local stovebolters have come through for me again. First it was cmayna helping me find a motor, now it's garandboy who thinks he might have an SM420 for me to drop in. What an amazing, welcoming, and helpful group this is... just plain awesome.

Do you want to sell the front half (transmission side)of your ujoint yoke and the speedo gear from your 3-speed tranny?

Can't tell you yet. I've been too busy to pull the old 235 and 3-speed. I'd like to have the pieces in and working before I sell off parts, just as a backup in case things don't go the way I want them to. If you're still looking in a few months, shoot me a line.