Try a Dana 60 from a mid-80s to mid 90s Dodge van or pickup. It'll get you a 3:54 ratio, 8 lug wheels, modern brakes. The most critical measurements are backing plate to backing plate and axle tube diameter. I put a Dana 60 from an 87 Dodge 2500 pickup into my '59 Apache. It was 3" wider than the stock rear, but it fit fine, axle tubes were the same size. I had to shorten the drive shaft ($120), buy new u-bolts ($20), and a new U joint yoke ($30), and get an adaptor to reduce the brake line from 3/16 to 1/8 ($2).
The original gears were 4:56, and I would run out of steam at 55mph with a V8. Now I can hold 70 all day long.
Chris
