Quote Originally Posted by RamAirZ View Post
Balance shafts go in the top of the engine, usually in the lifter/intake valley, here is a 4.3 V6 balance shaft...Not all motors have/need them but they are used in some.
Well, that's a new one on me!

What does a balance shaft "balance". I saw an exploded view of the 3.5L and the crank appears to have the tradional counterweight lobes. Why wouldn't that balance the rotating assembly?

Why build an engine with "extra" vibration if it could have been avoided with this part?