My F150 acts like it is popping out of gear from the 1-2 upshift under hard accelleration. At WOT, something slams at approx. 5000-5500 RPMs like it's popping out of first gear, the engine free revs and then slams again like it's popping into second gear. Is it possible that it's the clutch pack in the rear end? I'd rather it not be my transmission or any pressure pistons.

Thanks in advance guys.


Oh yeah, its a 1997 w/ the 4.6L, 2wd, and LSD.