69 Barracuda Clutch Shake Help Needed.

AJ/FormS said
Good call!
But if it was thaaat loose, I expect it would really bang during the shift, and any time the power is shifted from on to off,as the engine falls down.

Correct. I have had a motor mount issue in past years and you would feel that on a 1st to 2nd shift as well. At least I did in the past.