I've found posi rearends in V-6 & V-8 mustangII cars. Sometimes you're lucky enough to find one with a 3:55 ratio. They're normally in the V-6 cars. Most of them are donor cars for streetrods but there are a few left in wrecking yards, most with the front ends gone. They normally leave the rearend because the 4 bolt rear is not popular but, the pumpkin will interchange with all the 8" Mustangs, Falcons, Fairlanes & Mavericks. Good luck with your hunt.