The crank pulley that attaches to the stock pulley is aluminum and not very heavy at all. When you crank the truck up if the balance is not correct then you will know immediately by the vibration of the engine. The point here is that some of the aftermarked crank pulleys have failed. I went the route I did due to the insight of Josh who works on these trucks and has seen first hand the problem. The choice is yours. I have had no problems so far and am happy with what I have.