Truck Shop
Senior Member
After removing cover on 14 bolt GM axle and finding the numbers--it's the rare 3.21 ratio.
GM called it 3.21 but 42 divided by 13 is really 3.23. Only made those from what I can tell
in 1982-83 in a 14 bolt and there are no replacement ring & pinions. Which is ok because
there is nothing wrong with this one, plus a good highway gear ratio with a 345 hp 383.
Should be around 2,200 rpm at 60 to 65 with 31's.
GM called it 3.21 but 42 divided by 13 is really 3.23. Only made those from what I can tell
in 1982-83 in a 14 bolt and there are no replacement ring & pinions. Which is ok because
there is nothing wrong with this one, plus a good highway gear ratio with a 345 hp 383.
Should be around 2,200 rpm at 60 to 65 with 31's.








