If I remember correctly there was a one year only of a certian type torsion bar, but not 100% sure, on the trucks 60 to 62/63, the only years that GMC put it in and I have a 4000 series that had worn lower ball joints, NO LONGER SERVICED is what I found everywhere, NAPA could have them sent out and reconditioned for 600 a piece, but I got lucky and found some nos from a 60 series Chevy that are identicle for 125 a piece, but this was almost 10 years ago.
