Are the dates on these posts accurate? First posts in October '04, now revived in April '06?
Anyway, I'd start with that list from the Centerforce website. New motor mounts and/or a tranny mount are easy to install, fairly cheap, and not a bad idea in a 35-40 yr old car. U-joints also never a bad idea, and get the driveshaft balanced too.
That said, I think the highest probability is either a flywheel or clutch assembly problem. I had severe clutch chatter with my kids' '65 3-spd. I had the OE flywheel resurfaced and installed a new clutch and pressure plate, some no-name brand from Mustangs Plus. The car drove fine for the first ten minutes, but as the flywheel became heat soaked the chatter would start. It was so bad I had to pop the clutch to get rolling from a standing start.
I put in a Ram clutch and pressure plate. No improvement.
I put in a billet steel Ram flywheel. Problem solved. I believe the OE flywheel would develop hard spots when hot.
I think your clutch fork has nothing to do with the problem.
Anyway, I'd start with that list from the Centerforce website. New motor mounts and/or a tranny mount are easy to install, fairly cheap, and not a bad idea in a 35-40 yr old car. U-joints also never a bad idea, and get the driveshaft balanced too.
That said, I think the highest probability is either a flywheel or clutch assembly problem. I had severe clutch chatter with my kids' '65 3-spd. I had the OE flywheel resurfaced and installed a new clutch and pressure plate, some no-name brand from Mustangs Plus. The car drove fine for the first ten minutes, but as the flywheel became heat soaked the chatter would start. It was so bad I had to pop the clutch to get rolling from a standing start.
I put in a Ram clutch and pressure plate. No improvement.
I put in a billet steel Ram flywheel. Problem solved. I believe the OE flywheel would develop hard spots when hot.
I think your clutch fork has nothing to do with the problem.