3gc

I get a clunking noise that seems to come from the transmission tunnel. It only happens when i'm going under 20mph and let off the gas. I took a look under there today with the rear suspension not loaded and tried to move both the transmission and the torque arm in it's mount. Neither one budged but the torque arm mount did seem a bit dried, but not to the point that i'd think it would give under pressure. I tried a search and didn't come up with much. Everone's problem was with their tranny mount and i'm fairly certain mine is fine. I'll order a new ES torque arm mount next week when i order my catback from summit but are there any other things that can cause similar symptoms that I should look at in the mean time?

Also, is the transmission crossmember fiberglass or some other composite material on 4th gens? It really looked like it when i was under there today, but that dosn't seem right so I figured i'd ask.