[b454rat]

I know GT4 is 3.73, GT5 is 4.10, GU6 is 3.42, I can go on!!!!! G80 is the code for locking diff, but anything late 70s and up won't have the clutch type posi. Only G and I think they are B bodies (Caprice, Impala LeSabre) will have clutch type posi. I look all the time in junkyards for rears and posi's and such, scary, I even know some Ferd stuff.....But just do a google for RPO codes, probly half million of them out there...