Pinion Shim not the problem???

the jeep...2000 with RE 3.5 full packs sits perfectly at 4.5, 8.25 axle, 242 case with the RE H&T, front driveshaft fully rebuilt, balanced all the jazz.

Put in 4 degree shims so my pumpkin pinion angle is 1 degree lower than the driveshaft angle. This is my problem...i have vibes at around 60 when i let off the gas. Through all my searching this would normally be fixed by a larger shim, in this case a 6 degree. However this would put my pinion angle on my axle pumpkin 1 degree above my driveshaft....

Any ideas on this one, ive been searching off and on for two weeks and havent come up with anything yet!
Thanks guys

edited to include that my front driveshaft was removed and did not change anything, so i reinstalled!

Have you checked your u-joints? If it vibes only after you let off the gas, it's a pretty good indicator that it's your u-joints.

For instance, if your u-joints are worn out, when you have your foot on the gas, you're putting the d.s. and u-joints under load; this keeps the u-joints in place. Now, when you let off the gas there is no more torque to keep the u-joints in place, so they vibrate.

i would think u-joints, but they have maybe 45 miles on them......and they are spicer

You can buy 5* shims?

What about the front shaft's ujoints? Or axle shaft ujoints?

Check all. The rear shaft is probably fine if it was recently rebuilt.

RCP if i buy 5 degree shims (can i even buy them?) wouldnt that go against common practice, orienting the pinion to a completely equal angle? Or is theory out at this point and i should just try a larger shim.

Blaine, i did take the front driveshaft out and drive it around with no change in the symptoms, thats why im confident in focusing on the rear driveshaft and angles associated with it!

Yes you can easily find any degree shim,you said you didnt like 4's or 6's sooo!

UPDATE after scratching my head for a year i finally tracked this down to the h&t flange on the output shaft of the tcase coming ever so slightly loose. Re-applied lock tight and vibes are gone. Had never thought to check that because i had never heard of it and would have never expected the lock tight to break loose!