so i guess im being a little assumptive to think that its my tranny but today when i started to drive my car (1997 camaro z28) whenever i pushed in the clutch, I got a loud thunk right from undernieth where my tranny is like something came up from the bottom and hit it. so i stopped imidiatly and looked undernieth my car and didn't see anything. so i continued driving and it continued. Its fairly inconsistant but as far as i can tell it happens if i decel dramatically, push in the clutch, let it out and other random time. it doesn't happen at the exact moment i push in the clutch but like a split second after i push it. Someone said it could be my u joint but idk. any suggestions. thanks guys

 

Broken transmission mount, or broken torque arm mount, or even a broken motor mount.