The stock tranny, it is a truck tranny it is pretty stout, well the manual is. The clutch is another issue all together, on the old S/C Cobalts that came before us, I believe they use the same clutch, they blow them all the time but they are getting some huge numbers on those cars. Lyndon Wester told me that he thinks the weakest link in out cars is the clutch, followed by the rear end. I just paid $1000 for and extended warranty for one reason only, the rear end! It sucks even if you don't mod the engine.