I swapped a newer rear in my 1 ton pickup, but it was 10 lug and needed special wheels to fit. It was what I wanted then, and what I need now that it's under my 2 ton..

For you to keep your original wheels means you need to keep about the same "wheel mounting surface" to Wheel Mounting Surface (WMS to WMS).
So get out your straight edges and a tape measure and take a trip to the junk yard or even a parking lot.

Most 3/4 and 1 ton trucks Chevy, ford, or Dodge have the same 8 lug bolt pattern. Do check the hub diameter to see that your wheels fit, I'm thinking the dodge axles might be the only possible problem there.

I'd start your search with ford van axles and widen (hopefully narrower) wink from there. You can likely live with an inch or so one way or the other, which would be only 1/2" per side, check the tire clearance.

Also check a Chevy 14 bolt from a cab and chassis, supposedly they are narrower, about 63.5" from WMS to WMS I think this is close to the original axle?

Try this thread, post number 8, for a little more info, and about disc brakes for the 14 bolt axle.
http://www.4btswaps.com/forum/showthread.php?t=7601

As a last choice you can narrow a used axle, or even buy a new axle built to your specs, try http://www.dynatrac.com/

Let us know what you find or decide,

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-