Does anyone know the correct belt P/N for an Inter-av alternator installation? I'm  currently using a Lycoming belt P/N 37B19774-374 belt. The problem with this belt is the pulley on the alternator in wider than the belt. Even when I tighten the belt it goes to the bottom of the pulley allowing the belt to slip.  I'm told the belt that came with the STC was a Gates belt. I can either change the pulley or the belt.       Mooney M20/E