Gotta chime in here.
My truck is a '59 Apache 3600 - 3/4 ton - that came with 4:56 gears in the Eaton rear end. I wanted a truly highway capable truck, so I ended up swapping out the entire rear end for a Dana 60 rear from an '87 Dodge 2500. I got 3:54 gears, so the truck can run on the highway all day and not break a sweat. Pretty much a bolt-in operation except for modifying the spring perches. The Dana is about 3" wider than the Eaton, but the tires still clear the fenders with no problems.
Worth considering.
Chris
