so I installed a rebuilt 9in and now I have a vibration I think it may be the driveshaft is the 6cyl 3 speed drive shaft to long with a 67 cougar 9in rear end? if not could the driveshaft need to be rebalaced or replaced with a v8 driveshaft? need help? 
what are the driveshaft lengths for a 6cly compared to a v8?
what are the driveshaft lengths for a 6cly compared to a v8?
