...can i just cut the yokes off of the old shaft and use them on the new tubing i buy?
You're asking too many questions for this driveshaft to have a remote possibility of being halfway straight...
...but here goes...my home-made, straight driveshaft tech...at least for a driveshaft with splined slip in it...
1. Cut the yoke, cv, or splined chunk off the tube just beside the factory weld on the side opposite of joint/spline. Prolly only have to cut 1/8" deep max. Cutting/grinding out the weld is time consuming and annoying. This should leave you some of the factory bevel to insert into your new tubing.
2. Eyeball the splined end straight into one end of the tubing and tack that sucker in there. Just one tack at the moment.
3. This could prove to be the hardest part. Find a flat surface long and wide enough to roll the driveshaft one complete revolution. Your partical boarded work bench prolly wouldn't be flat or true enough to pull this off. Possibly a nice metal work bench or an unbashed portion of concrete floor.
4. Get out your adjustable square and measure from your flat surface to the top of the splines while the shaft is laying there. Roll the shaft some (1/4 turn or so). Measure again. Repeat. Find the high point in the rotation and tap it down until it's true. Tack again.
5. So when you tacked again it probably moved out of alignment again. So you'll have to repeat step 4 until your tacks don't adjust the splines any further.
6. If that last good tack didn't cause any movement then you should be able to weld her up solid and not worry about further movement. I usually have 4 good tacks at this point and weld in between them. It'll prolly move a little again but if you started straight then it wont be enough to throw it into a vibration.
7. Measure for proper tube length and cut to appropriate length. You're on your own for how to measure. You're a big boy you can figure it out.
8. Slide in your other yoke/cv, eyeball it straight, and tack it in there. Bolt the whole shebang into your truck with it jacked up and in neutral.
9. Get your buddy to spin the tires for you while you watch the shaft at the newly tacked in joint. You can use a dial indicator to find the 'high' side and start the tapping and tacking process again. If no dial indicator you can tack a piece of metal real close to the shaft for some reference as it spins. You want to tack and tap till it's true and, again, doesn't respond (by moving) to the last tack.
10. Weld that up. Take it outside and do a couple burnouts to make sure you can weld.
Should be a straight, non vibrating, completely retubed shaft now.
It's even easier if you don't have to worry about welding in the splined end...as in shortening a shaft.
There...that's my first tech writeup ever...enjoy...
