The rear end on my 92 Chevy half ton with 4.3 litre 6 shelled out this weekend. I bought it new and it only has a quarter million miles. I have the original window sticker and all it says is "locking differential". It doesn't give any gear choices in the owner's manual either. I know it had some tall gears, and I have to go back with the same ratio so it matches the front differential. I can't just jack it up and turn it to determine ratio, because it is locked solid. We had to skid it off the trailer when we got it home. Any ideas?