Didn't mean to amke you feel bad or anything, just trying to figure out what you got. The hubs on the rear are normal for a 3/4 ton (or at leaast on the older ones) that use the full floating axle. The bearing setup is more like the front, with an inner and outer bearing. The axle itself doesn't carry any of the weight, unlike a semi float like what a 1/2 ton (or late model light 3/4 ton) would have. Most likely, it's an Eaton HO52, with the 4.56 gear. Easiest way to et a more highway freindly gear would be to swap the rearend out for a later one, Dodge and ford 3/4 ton vans are close to the correct width, though many are not full float.
You might also search the site, I do beleive that there are a couple of guys working on a disk brake conversion for the 3/4 tons that keep the stock front axle.
