2002 Cadillac Escalade lifters

If you can determine that it is rhythmic with camshaft speed, it could be lifter, rocker arm, or something of that nature. To narrow it down(not isolate), you would first remove the belt, and then kill cylinder power one at a time. You could do this by disconnecting coils or injectors. That may or may not make a change. You can also run the vehicle with the cam cover removed, but it is messy.