Okay I bought a set of asp under drive pulleys for my 02 mustang used for $50. It came with the crank and water pulley but no altenator pulley the guy said he just used his stock one cause they were the same size but he had since lost the other. My mechanic friend said if we put them on I would have charging issues. My question can I just use the stock one or not? The guy I got them from is a great mechanic him self several mustangs including an electric fox so what do I do? I drive it maybe a couple times a month but sometimes more than others any advice will be nice