This is my plan with a 51 3/4 ton:
3:42 rear from a 4wd S10. Locate axle back to center in wheel opening, use original springs. Driveshaft should bolt up with the correct ujoint. Keep the six and four speed. Change front axle bolt pattern to match the rear(5 bolt drums if there's an easy way).
It's a plan and it is more involved than it looks. I'm sure someone will chime in that knows more than me.
Jim
