69 Barracuda Clutch Shake Help Needed.

Did you soak the bushing in oil and wipe dry prior to installing it?
Is the input shaft whole and the original length?
You mention it is all original, how sure are you? Lots of 833's have been modified over the years and the shafts cut. What about BH run-out? How is the ride height and does it have original type shackles? Just guesses for you to ponder.
If you need an angle on the pinion Myself or other could surely measure ours for you.

If it is all original it would be nice to see it posted here Show "YOUR, REAL" 383/440 '67-'69 Barracudas...NO CLONES please