vibration ?

[chatcher]

up around 80+ mph i notice a pulsing vib from the rear of my car i have replaced virtually every thing i can think of back there but have not fixed it my last areas of concern are the wheels and rotors i believe i over torqued the aluminum wheels when i first got them i used to use the crank on it till you cant crank any more method but i have had them off and taken to a tire place and rebalanced not sure if anything i would have done to them would have shown up on the balancing machine or not also the rotors behind the wheels of cousre were subjected to the stress of my ignorance of torque specs the thing that confusses me is that it is not a constant vib but a pulsating one it has new polyurethane bushings on the rear end itself new upper and lower control arms new aluminum driveshaft new springs replaced axleshafts new shocks and updated sn95 brakes if it is the wheels is there any way to tell other than getting new wheels i have rotated them to no avail what else could it be? any help will be greatly app