Ok be prepared to cringe....my basic question though is how long should a driveshaft be?
I've got a 72 cutlass with a 72 chevy 10 bolt 2.73 rear end, a 72 Olds driveshaft for a Muncie (Th350 yoke, long shaft), connected to a modified 82 f body B/W T10, and an LSx motor.
The motor/mounts move the motor/trans mounting face forward about 1/4". But the T10 is about 1/2" longer than the muncie.
With the Chevy 10 bolt, I hear it's about 1/2" farther back so now we're at about 1/4" short of spec.
1) So...what's the optimal yoke length inside/outside the trans bushing.
2) I'm obviously not binding on the speedo gear or extending too far with suspension cycling, but what clearances or angles are critical?
3) Can you compensate a short driveshaft with a longer yoke?
4) What are the symptoms/results of a too short shaft?

 

OK, I answered my own question. There was 1 3/4" from the yoke to the trans seal. The 72 has a short yoke that's only 5" from the U joint center to the end of the yoke. That actually puts the yoke end behind of the front of the T10s tail bushing. Not a good situation. I've been driving it like that for 5k miles. There was a noticable groove in the yoke where the rear of the tail bushing rides.
I ordered a 56 1/2" driveshaft, complete with yoke and U joints.
Also going to check the tail bushing.

 

I don't believe 1/4 inch is going to matter.
I have used a longer yoke to compensate for a short drive shaft with no problems.
As long as most of the yoke is installed on the tail shaft you should be fine.