The 1/2 ton rear will hold up fine to relatively light loads, but not well to going with the full load that the 3/4 ton can hold. If it is an Eaton, than the available gearsets are very limited. I'm not even sure if anything is available in the line of gears for them, mainly soft parts like seals and gaskets. If it has the Spicer/Dana (most likely a 70) that opens up a very good gear assortment, running from 3.54s up to the 6.00s range. Just from what you describe, it has the std coil spring rear with the single helper leaf. My Dad had a '71 with that setup with the Eaton rear. My Granpa (Moms side) had a '69 Camper Special w/ leaf springs, it had the Spicer/Dana 70. A later diff (like a 14 bolt full float) coild be swapped in, you would just need to swap the mounts for the springs to the new axle, which will require some welding. For the front, you can do the same swap as a 1/2 ton disk brake/spindle swap, just use 3/4 or 1 ton parts. I think the lower balljoint is the same, it's the upper that is different. I've heard that the outer tie rods are different, too, so those may have to be swapped as well.
Oh, one more thing, yes, lots of hear choices for the 1/2 ton axle. GM used the 12 bolt up into the '70s, so there are parts available for it.
Last edited by LONGBOX55; 04/17/2008 3:09 AM.
