Tranny sounds like a rock crusher!!

[smokedchevy]

Hey guys. My T-5 tranny in my 92 is sounding really bad. It just started. It sounds like a rock is being thrown around in the tranny. It doesn't do it all the time. You can hear it rattling around. If you play with the RPM's for a little bit it sounds like it gets picked up and thrown around and then settles back down again. I haven't done anything to the car lately. A few weeks ago I replaced the harmonic balancer and pulleys and installed an electric fan, but it did not make that noise. Having the car in neutral or in gear does not seem to matter. I've also pushed on the clutch while the noise is there and it still does it, so I'm not sure if the throw out bearing is at fault. Any ideas?? The tranny also has 172,000 miles on it. It shifts and drives fine. Thanks.