FWIW I had a similar problem a couple years ago on my 'T and it turned-out to be a bad rear wheel bearing.

--Kevin


'93 T100 4x2
26MM Torsion bars, Bilstiens and RS9000's, Firestone air springs, 2.25" Magnaflow exhaust, Hella 550 driving lights, etc.
'99 4Runner Limited 4x2 -- Hers
'87 Toyota X-Cab -- Her Kids'
'04 Silverado Crew-Cab P/U -- Toy Hauler