The early 1/2 ton rear ends were 6-lug, and didn't offer much better gear selection, 3.90:1 instead of 4.56:1 or lower. There are plenty of suitable 5-lug later model rears that work well, clear up to 3.08:1 or higher. A Chevy Astro van rear has a pretty good ratio selection, and about the right width, etc. There should be lots of threads on the subject if you use the "search" option. If you're going to eliminate the 8-lug rear axle and front hubs, it makes sense to upgrade to a much newer axle and brake system, possibly 4-wheel discs, or at least a power-assisted disc front/drum rear setup with repair parts more available than the 50-year-old original brakes.
Jerry
