i have a 67 with a four speed and when you let out clutch it chatters it only does it when the car is warmed up doesnt do it when cold and only does it in first gear is it the clutch or flywheel? any suggestions appreciated graemlins/clonk.gif

Could be both. Either hotspots on the wheel or contaminates on the disk.

How new is the assembly? How long has this been going on? Did it do it when it was a fresh install? When they surfaced the flywheel did they just 'surface' it or was it 'ground' finished? (one is a single point cut and the other is an actual abrasive grinding cutter)

If you allowed the weight of the trans to hang from the input shaft during install without the pilot shaft being engaged in the pilot bushing, you can screw up the clutch disc to the point of causing "chatter". I speak from experience. :(

I quit buying rebuilt discs because they were so prone to chatter. I figured they didn't replace the springs. Never had a problem with new ones.