Finally getting my truck together after several years and have run into a hmmmmmmm. Have several boxes of parts I am sorting through to put this engine in. Came across the crank pulley for the AC and 2 different diameters. Small one is 4.75 and the other 5.5. Truck is an 86 and parts boxes are 86/87. My truck began life as a 2wd and parts boxes are 4x. All have/had AC and PS. Any insight on why a different diameter bolt-on pulley? All trucks 22r and re