I know I have read some post on firuring out what you need to change for pinion angle to fix vibration but I can't find it.

I have a TKO-600 in a 1971 Cuda. For initial set-up I have the tranny at 3-1/4 deg down the the pnion at 0

I have no vibration going down the road until about 70mph.
I have no vibration under decel
I don't think thier is any vibe under hard accell, but it is hard to tell as the power coming out of the Hemi seems a little violent making vibrations hard to pick out.

What I do have is a pretty good vibration when I push the clutch in and coast down the road. The same vibration when going down a hill and off the gas. Aslong as their is back pressure on the drive line it is gone.

I was going to get some shims to turn the pinion, any good guess on which way to go.