drive shaft
 

Ok, here is the problem to solve. On my 69 coupe the drive shaft is vibrating. I got the u-joints replaced and it balanced. But it still vibrating. The only times it vibrates is when exiting the freeway and at a sertain low rpm. Any suggestions????????????

Have you checked the pinion yolk?
This would not be the first one to work loose! Its a fact that this will cause a vibration on deceleration.

if the yoke is tight,check your pinion angle
if it is off the rear end will not be at the same angle as your crankshaft/trans and will cause the driveshaft to whip