[Dick]

Hi Guys,
I found the part that was causing the violent chatter. I wouldn't have thought of looking at this normally but was inspecting parts as I was removing the transmission. My helper noticed the throwout bearing hub wasn't sliding smoothly on the input shaft retainer.
I just happened to look at it while having coffee and spotted the problem.

The bearing is on the hub crooked. It's at an angle. I guess it would have acted like a cam lobe to the pressure plate fingers. It must have been driven onto the hub rather than pressed??

I still have a bit of a shudder but it's probably from damage done with this throwout bearing. I'll fix the rest when I change to an OD transmission.

Thanks to everyone that posted on this thread from the beginning as it save a lot of parts and labor!
Dick