Rebuilt 904. Whirring. Dead?

I think it would have to be in the torque converter or front pump.
The 904 in our old 73 Valiant made a whirlly noise its whole life, 308 K miles. Worst sound inside the car was sort of a lew lew lew lew through 1st gear. Trans tech at the Ford store where I worked said it was the front pump and it would eventually wear out the front case.
Good luck with it.