sixth-and-redline

Alright so its a 94 6speed z28 and unless im really giving it hell it jumps and "studders" under acceleration. The engine revs up just fine and clutch doesnt slip at all. Could this be my tranny or mabey the rear end? I dont think its the motor. sometimes there is also a knocking sound under full throttle that will hit mabey once or twice throughout the gear? any ideas??