Back to the beginning...
If you want faster gears and modern brakes under a 1 ton AD truck the easiest and cheapest is a nerer 14 bolt rear axle swap from a GM "cab and chassis" pickup (without the pickup bed).
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Grigg
Another option would be a Dana 60 from a Dodge or Ford van, which tend to have a 3.55 ratio. The later Fords are also very common with rear disk brakes.
