rear axle codes/options 92 S10

got a buddy of mine with a 92 s10 with the 4.3 and four wheel drive. He says I can have the rear end out of it to put under my S10 that has the 2.72 rear. I was wondering what rear end options came in the 4x4's. I figure if it is anything between a 3.42 and a 4.10 it will do for me but didn't want to go through the hassle if I could end up with what I already got. I know there is a code located in the glove box but don't know which set of numbers means what. could anybody tell me exactly what number to be looking at and which number means what with respect to rear end ratios?

Thanks in advance.

I believe that from 89 to 95 they ran 3:08 or 3:42 for rears. Unless it has a factory set up for towing, then it may be a 4:10.