I think I may have found the problem. After closer inspection I noticed a bur on the pressure plate where it seats into the flywheel. After filing it off and reinstalling the clutch the vibration is almost gone. My comment on the pilot shaft came from one service bulletin I found but it is talking about the model 65 and 75.

Where Are You From? Mount Pleasant, Iowa

Do You own a car built by Durant? 1928 D-55 Coupe