I've been chasing a vibration for a long time from the rear forward. New tires, axles, bearings, ujoints, balanced four different ways.... etc, and have made my way towards the tranny. The shake follows engine rpm and not travel speed... worst around 2500, Drop it into neutral at cruising speed and it goes away. Get on the gas at highway speed and it shakes like a wet dog. A fellow at the drive-shop thought it may have the wrong flex-plate. It a 350/350 combo, with center-bolt valve covers. Hencho in Mexico. I've been having a tough time getting any readable numbers off it. I see the flexplate has a weight, does that tell me anything... What else may tell me if this is the right or wrong one?