One rear axle that might be worth a look is from the Toyota Tundra V8. I was at a Toyota dealership recently and they had one removed for some reason. That thing is massive! It's got a 10.5 inch ring gear, and comes in ratios from 3.60-something to 4.30, with a couple of ratios around the 3.90 range. At first glance, I thought I was looking at a HO-72 axle! They also come with disc brakes on some models. If the wheel mounting flange width is pretty close to right, it might make for a pretty good swap, especially paired up with an OD transmission of some type.
Jerry

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