The Stovebolt Site Forums The Shop Area Driveline 55 1 series trans numbers identification

I have a 55 1 series 3100 with a three speed with overdrive and the only numbers I can find on the trans is on the left side and are 3846122 and under that number is 1237. Is this original trans or has been changed out at one time. I can't find any letters with numbers. Thanks for any thoughts on this matter.

Can you post a few photos?

It looks like there were no optional overdrive transmission available for trucks in 1955-1st series. However, a factory overdrive was available on Sedan Delivery and cars in 1955 (all year).

Do you know what year rear end you have? An overdrive with the original 1/2 ton 3.90 rear end would be a nice highway cruiser.

I checked my rear end ratio today and its a 3.90 with NK1018 numbers on it. The engine block number is 3835911, Head 3835913 and serial on block is 0059235F55X. The trans is very oily and has alot of grease caked up on it but I got the numbers GM 14 3846122 1237 off of it. My eyes are not as good as they once was up close. The overdrive wiring is in bad shape and is not fully connected so I don't know how long it hasn't worked. I have just started on this project but I already like what I see. So far I have determend its a 55 1 series 3100 five window delux cab with 235 engine, 3 speed w/overdrive and a 3.90 rear. Tires are 6.50-16. From all I here it should make for a nice setup. Thanks for any help.
55overdrive

I forgot to mention it shows 32295 on the odometer. I don't know if its only 32295 or 132295 but it runs good. I know that 3500 miles a year was alot back then, not like now days. It's still on 6 volts and all looks original. I don't have any brakes yet so thats my first job so I can check it out more. I just drive it out in the pasture for right now.

Sounds like a nice find. I agree the 235/OD/3.90 combo will make a nice runner.

There's lots of original OD documents copied here. The wiring diagram is for something else but it helped me wire the one I put in my '54.

Read about how it all works and you should have no trouble re-wiring it.

Nice photos. Nice truck.

Maybe someone can ID the overdrive unit?

Here is an OD diagram from Deve's website (posted by Cletis). (the date is not shown)

Maybe the "1237" in "3846122 1237" is a date code?

It looks like a garden variety 3 speed overdrive to me. 58-65 units had a rear mount pad so it appears to be the correct for the year. 55-1 trucks had an open driveshaft so they may have offered the OD as well. Even if it isn't stock it's good to have.
Fred