Well, the Chevelle is D.O.A.....

[VintageMusclecar]

Not a Mopar and not a Tremec.

I'll post up the details once it's here.

John, at this point all I can conclude is that the shaft was junk from the beginning. That still doesn't explain why the 2nd shaft also had a vibration (out of balance or warped also??), but at this point it's water under the bridge. All I can do is pick up the pieces (literally) and move forward.