Sounds like a suitable axle for your application.
But I am a bit confused, you say it is nearly the right width, and that you need adapters for the dual wheels?
Did your truck come stock with dual wheels? And is it really a 3/4 ton? If it were an AD model You could only get duals in 1 ton and larger...
You should be able to physicaly bolt dual wheels on without a problem even though it was intended for singles? However, the way the hub bearings are spaced in relation to the center of the wheels (load) may affect the life of the bearings if you switch to duals? This assuming the 60 you found has singles.
If it is a bolt pattern problem you have I would not use adapters, I would either find an axle with the pattern you need, or the wheels to fit the pattern you have, probably hard to find duals with fewer than 8 lugs.
Spring pearch spacing is easy enough to correct with some carefull measuring and welding. It should be exactly what the original was.
Driveshaft can probably be reused from original, length is proabbly exactly right and joint size too. In my 52 1 ton with a newer Dana 70 I had to shorten my shaft 1.375". The 60 is not quite as long as the 70 from center of yoke to center of axle, so you should be really close on the length of teh original shaft for working with a 60 axle. The Spicer U-joint size is 1350 on my 1 ton, and probably your 3/4 ton too. Dana 60 and 70 axles are most often equipped with 1350 size joints. New yokes can be purchased for about $65. I'll even have an extra when I switch my driveshaft to 1610 size joints soon.
