The 665 (actually 663 IIRC) belt is the stock length S/C belt, and should work down to a 3.6" pulley. A 660 (K060660 in Gates) is typically used for a smaller pulley down to 3.25"ish. That K060841 doesn't match any application for any year GP I can think of. It's too short for the S/C belt and too long for the accessory drive.