1992 Camaro RS w/305 Automatic

I just replaced the tranny mount, so that's not the problem. I replaced it because on acceleration my tranny would make a "clunk" sound. That is fixed now. The other problem, though, isn't. Occassionally, but not always, my car makes a sound on acceleration that is like a high pitched whine/grind. It shifts fine under normal accelleration, though the noise accompanies if I push the gas just a bit hard and is more apparent at low speeds. It's almost like a slipping belt, but I just replaced my belt and that isn't it.

The noise isn't constant, but there is a faint knocking sound from time to time.

U-Joints? What else could this be, perhaps?

 

Turns out my starter bendix spring wasn't engaging and the bendix was flopping around, occasionally hitting the flywheel. New starter has fixed the problem.