The reason I ask is I was running a SS deep grove pulley on my Hemi and the alternator would never charge on idle because of the diameter. At night the lights would dim until I started to move. After years of procrastinating I finally changed it to the correct pulley,which is about 2 5/8" dia.Now it charges all the time. I can't remember the exact dia of that SS pulley,but it was between 3 3/4" - 4". The good news is if it is a SS pulley, Kramer gets $150 for them,so you can sell it like I did.