The Stovebolt Site Forums The Shop Area Driveline 55 transmission on a 54 driveline?

I have a buddy with a 4-speed transmission from the 55 1st series (open driveline), and I'm interested in replacing my three-on-the-tree transmission with his. Would I also have to covert to the open driveline instead of the torque tube?

And then if I would have to, would I also have to swap out the rear end to accept the open drive shaft?

The rear extension housing and yoke on the 4 speed can easily be swapped to one for torque tube drive.

Any idea if I could just take those parts from my 3-speed? When it comes to these I6's and transmissions I'm still learning

The parts that Pre'68 Dave is referring to are different three speed to 4 speed. But the parts will fit on the open style transmission. Find a bad 4 speed and rob the parts if you can. You might need to find the "ball and tube" from a 4 speed to match it all up. I think. Some one will know for sure. Does any one know if the torque tube is longer or shorter with the 3 speed? Seems to me the torque tube is the same but I have been wrong so many times I am used to it by now.

The torque tube is the same length from 1948-54 no mater if it was 3 or 4 speed. Trucks with a automatic trans had shorter torque tubes
The bell is also the same 3 or 4 speed.
The SM420 4 speed extension housing and yoke you need fit 1948-54.

my question is why are you interested in this change? is the 3 speed bad? are you having trouble with the column shifter? do you think the 4 speed will improve something else?

Bill

Generally I just prefer floor shifters over column (just what I'm used to). The three speed works, but the column pieces are very loose and flopping all over (I know I could replace these). The previous owner tried to modify the column shift somehow and botched the job (not quite sure what he was doing).

I figured if I had the 4-speed available, and it was a relatively easy swap, I would just switch them out. I'm not looking for any performance gains or anything like that.

You could always try this: http://www.summitracing.com/search/product-line/hurst-mastershift-3-speed-shifters/make/chevrolet
It aint "stock" but would replace the column shift issues.

Just another quick question. My buddy said he would give me the driveshaft with the transmission. Which would just leave the rear end 'torque-tube style'... could it be as simple as changing the third member and gears to an open driveline style? Say, take the third member from a 55 truck?

You can put the Rear end from a 55 in to your AD truck. You will have to change the locating pins or the mounts on the rear end. I wont drill into springs for any reason so I would change the mounts to locate the rear end in to the correct location. That would mean some welding and careful measuring. Quite a bit of work for the same gear ratio. Look for an older SM-420 and take the parts off of it. Would be easier and cheaper I think.

Get the springs from the '55.1 also and you can bolt it right up.

Thanks for all of the advice on here fellas! After talking to my buddy he's also gonna throw in the rear end with the tranny and drive shaft! Looks like I'll be good to go!