Rebuilt 904. Whirring. Dead?

i agree with j5. ive only rebuilt a couple of 727s and so far no problem with em. since you said you have a shift kit in it and possibly a stage 2 id be careful when it shifts cause i have a reenginering kit in my truck and my duster. when i got my truck back the shifts were hard enough to hit my head on the window but yet my duster doesnt shift as hard and ive done all sorts of lil tricks my boss knows to get firmer shifts. but i would look at both sets of planets. pump wont do any harm if you installed the converter all the way in