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FRT, I used to go round and round with this very same question on my 1.5 and 2 tons. My multivariate analysis boiled down to two questions; which bolt pattern could I live with, and how wide was acceptable in the rear. Truth is, our Job Rated medium duty trucks are pretty narrow, when considering modern rear axle swaps. Front axles, too. Narrowest I could find in modern hardware came under cab & chassis setups from the big three. Think ambulance, wrecker, box van. Beware their ring and pinion ratios are wildly different by intended use and original powerplant. The width in question here is WMS to WMS (wheel mounting surface), unless you're in love with one axle setup and are willing to have tubes and shafts cut down to the width you seek. Lug pattern. Our 5-lug pattern is an 8" on center. The newest axles I ran across were a brief two or three year blip of Dodge motorhomes (MH) circa 1972/1973. The axles and hubs are expensive, and the wheels (19.5" tubeless), expensive as well. I think the last set of MH wheels I came across were 17.5, but I may be misremembering. For rears, my '47 COE runs a Dana 60 with an 8 on 6.5" pattern. My buddy's '59 Montpelier (Dodge flathead 1.5 ton chassis) step van runs a Dana 80 out of a wrecker, and runs slow, with the Furd 10 bolt wheels on it. A 5-lug problem solver, maybe, I had a '58 D400 with an Eaton 1350 or 1380 rear end, single speed, 5 lug on 8" circle matching the pattern under your Dodge now, it had Budd 20" lock ring wheels. And, the front axle; on my '47 COE, I run motorhome disk brakes, thanks to a spindle swap at the kingpin; the kingpin on the COE's and buses were 1.12" diameter, the same as the class A Dodge motorhome chassis from the '70's. M375 or M400 chassis, usually with the 413 and industrial cooling setup, knock the pins out, swap the knuckles over, put the pins back in and put in fresh welch plugs. All Mopar parts, and the engineering didn't outpace the application in those 30+ years. So, for my COE, that runs 8 lug on 6.5" bolt circle, plenty of wheel and tire options there, just not as large as an 8.25 R20 setup. Did this on the Montpelier, too. There's single and dual piston calipers, so size yours accordingly for your needs and intended uses. As far as keeping it original, my buddy's original '41 COE travels at 48 MPH. Crank the windshield out a bit, and it's a nice, cool, airy ride. Good luck with your pursuit! MBSoPaB

Well I just stumbled upon the flushing saga. Too late now, but my choice would have been automatic dishwasher detergent. No bubbles and one of the strongest cleaners available, especially when dealing with grease/oils.

The choice of parts depends on which donor rear axle you choose to go with. I ended up using a Dana 44HD-A rear axle from a 1997 Jeep Grand Cherokee with 3.73 gearing and disc brakes. It was the first one I found that matched my criteria. Changes involved removing all of the old perch mounting hardware and adding new replacements. For the most part, after getting the new perches set up correctly it was a drop-in replacement. You can read about my rear axle conversion here.