Okay, here's my problem. My whole drivetrain shakes violently when I release the clutch quickly, doesn't matter what gear it's in - it even does it in neutral. If I release the clutch slowly and easily it acts normal. The jeep is an 81 Scrambler with 258/T-18/D300, year old Centerforce clutch, new motormounts, and new u-joints in the driveshafts. I checked the bellhousing bolts but they're all tight. When it shakes, it's hard enough that it flexes the skidplate and the vibrations just increase with rpms. Any help would be greatly appreciated.