I have been fighting a driveline vibration for some time and finally had a chance to look into it further. Had new driveshaft built and balanced. Put a dial indicater on it the other day and have about .025 runout. Turned the shaft 180 degrees and high spot moves 180 degrees also. Measured distance on ujoint caps and it points to a bad pinion yolk. It's not worn that I can tell so maybe machined poorly!!. Any comments.

Also what yolk will fit. 8.5 inch diff with inside clips out of 73 Camaro or Firebird.

Either like you stated poor machining or the wrong U-joint used. Reads like a Powerglide U-joint used in a TH350 yoke, or yoke is spread apart too much.

Distance measured from cap to cap should be 3 5/8 inches for a TH350 U-joint and 3 1/8 inches for a Powerglide U-joint.

Both caps should be seated inside the yoke tabs and clamped securely regardless which U-joint/yoke used. graemlins/thumbsup.gif

Are you sure the PG and Th350 take a different U-joint, Everett? I always thought the size change was with the Th-400. However, I've been wrong before!

I'm talking about the diff pinion yolk. I'm sure its the correct ujoint, there is maybe .005 play between the bearing cap and the yoke when you push up on it, against the inside clip.

I have seen several yokes that were machined off center. You could try to repair yours by brazing the tab on the wide side and machine it again. You could do this with a die grinder if you have a way to accurately measure it.

BPOS, I could be wrong as well.........

I'm surprised BGH didn't mention the difference. ;)