If you feel vibration in the steering wheel its the front tires out of balance. If you feel it up through the floor and seat then its likely the rear drive shaft. Have you checked your u joints for slop? They more often than the carrier bearing are responsible for vibration. Sorry to hear that you already dumped a pile of money into tires/wheels and shocks when they probably were never the problem. <img src="/forums/images/graemlins/frown.gif" alt="" />

'04 Taco x-cab 3RZ FE stock (daily driver)
'90 x-cab 22RE stock
'82 Hilux 6" lift (ACES HI)
'82 2-Hiluxs' Rally Edition (parts)
'81 Hilux 3" lift (parts/restore)