i just picked up a 1997 gmc sierra 4x4 cheap. 5 speed manual. once in a while (often but not regularly) it makes a grinding noise while upshifting (never down) and sometime you can feel it in the stick, somtimes in the clutch pedal. doesnt feel like gears grinding though. sometime it grinds after its already in gear till you release the clutch pedal. drives perfectly fine though with no clutch slippage or popping out of gear. so im not sure what to think, any ideas? thanks (it doesnt grind when shifting into reverse so im sure the clutch is being fully released, and when you just keep hitting the clutch after its in gear theres no strange noises. and no abnormal noises when clutch is depressed at red lights and whatnot)