Long to Short Swap driveshaft question

[BigCarl]

Hi guys, I have been trying to figure this out for a while.

I currently have a 1972 GMC fleetside longbox with a 350 small block (which I have swapped from carbureted TBI) and a 3 speed on the tree which I wan to keep. I want to take my cab, engine and drivetrain and swap it over to a shortbox stepside.

I have a shortbox frame and I have a stepside box.

Is the shortbox driveshaft a 1-piece or is it a 2-piece with a bearing in the center like the longbox? Also, does the shortbox driveshaft have a slip yoke or a sliding shaft?

[brad_man_72]

The only 2wd 67-72 to get a one piece shaft was the swb equipped with a 6cyl and 3 speed. Everything else had a 2 piece shaft. Trailing arm trucks didn't have a slip in the rear shaft, leaf spring trucks did have a slip in the rear shaft.

You will have to have your driveshaft shortened and ballanced or you can have a one piece made using your trans yoke (to save a few bucks).

[Motoxrrar]

I had a one piece made for my long bed only cost about 200$

[WIDESIDE72]

I have swapped 700r4's into a couple of 71/72 swb trucks. I used the one piece ds out of the same trucks as the trans.( 82-87). I ground the rivets holding the carrier bearing for clearance.

[BigCarl]

Thanks guys. Any and all input is good.

The short frame that I have is a trailing arm frame and my long box also has trailing arms, so its basically just going to be a change over.

I have an extra long box 2-piece driveshaft that I can get shortened, but if I can find myself a 1 piece driveshaft, I may go that route.

[brad_man_72]

Originally Posted by BigCarl

Thanks guys. Any and all input is good.

The short frame that I have is a trailing arm frame and my long box also has trailing arms, so its basically just going to be a change over.

I have an extra long box 2-piece driveshaft that I can get shortened, but if I can find myself a 1 piece driveshaft, I may go that route.

Find?

I've built dozens of one piece drivelines for these trucks both swb and lwb. Hell I've built 3 just for my truck alone (moving the engine and trans around and ls swap). I don't see how finding a driveshaft randomly would be any more cost effective than havig one built to the length you need. Or having yours shortened and ballanced if the shaft is in good shape. I've seen way too many junkyard shafts that need more work than they are worth. Usually the forklift operator trashes them if the wreck didn't.

[Keith Seymore]

Originally Posted by brad_man_72

Find?

I've built dozens of one piece drivelines for these trucks both swb and lwb. Hell I've built 3 just for my truck alone (moving the engine and trans around and ls swap). I don't see how finding a driveshaft randomly would be any more cost effective than havig one built to the length you need. Or having yours shortened and ballanced if the shaft is in good shape. I've seen way too many junkyard shafts that need more work than they are worth. Usually the forklift operator trashes them if the wreck didn't.

x2. This has been my opinion for a long time.

Not commenting about this original poster - but - I've never understood how guys would spend thousands of dollars to do an engine/trans swap and then finish the job by installing a scrounged junkyard shaft.

By the way, BigCarl - I always prefer a one piece shaft whenever I can get away with it. Less complexity, fewer moving parts, etc.

K

[Motoxrrar]

You won't find a one peice drive shaft. None came stock with a one peice except s6 with 3 speed. If you have trailing arms you may have to cut out the drive shaft loop in the center cross member. Or lengthen it. What I did was take some 3 x 1/4 " plate and bent a half round out of it approx. 8" long and cut the bottom loop out then welded my plate in place. This gave me another 4"-6" in travel for my drive shaft