Rear Axle Assys - Complete

[Richard C. Howard]

Hello all..... new member here, thought there would be more posts in the archive but it seems that there's not many of us '73-'87 GMC & Chev folks around anymore.

I've got an '82 1500 GMC 2x4 that I bought used some years ago; truck is in very good condition after my work, maintenance, and the good care given it by the first owner. Mileage is shown as 235K and I believe this is accurate.

The rear axle has the common 3.42:1 ratio and I believe it's the original still surviving with clean lube always in it. It is however showing its age with some slight gear noise.

Questions: Instead of rebuilding the existing differential, what complete rear axle assemblies from the 3/4T / 2500 series could be installed in my truck as a bolt-in replacement. I'd prefer the lowest ratio that was available in these 3/4T axles in order to keep the engine revs down. Is there any 3/4T axle that's considered better than the others? Limited slip is not a necessity.

Thanks very much for any information and opinions.....

[fast68]

well i believe you are confused about terminology here so i will clear some thing s up for you first
regarding axles and ratios


ratios such as 2.73 and 3.07 are called high ratios and ratios such as 4.10 and 4.56 and such are called low ratios

you wont find high ratios in any 3/4 ton or 1 ton axles but you can find as low as 3.73 in the 1/2 ton axles, 10 and 12 bolts,

axles under 2wd 67-72 1/2 and 3/4 ton and also all 1/2 and 3/4 ton in 73-87 will swap because they all have the leaf spring perches set apart the same distance, 42.5" center to center, you need to decide if yuo want high ratio for highway use, or if you want big heavy axle, in which wil not have highway ratio in it


63-72 axles for leaf spring will fit under the 73-up trucks except that the shocks mounts changed in 73 so that one shock is on one sid eof axle tube and the other one is on opposite side of the axle tube, in 63-72 they were both on same side of axle tubes as each other so you would need ot modify that and then you would be fine