makes a grinding noise and sometiomes wheels thump and/or tires slow and truck on 2004 Ford Explorer

drifts Could this be awheel bearing or a differential
I had the tranny flushed, mechanic said it was ok

Asked by for the 2004 Ford Explorer
I have a 2003 Explorer and just had wheel bearings and brakes replaced, expensive but solved the problem
how many miles on ur truck
my problem seemed to happen after a brake job