Very common to do in this area for race cars and 4x4's. Many drag cars, Jeeps and Broncos run around here with narrowed Dana 60's under the rear of them. Roundy round race cars and street rods use 9" Fords. Moser Eng. in Indiana (I think?) can shorten and respline your axles very reasonably. Didn't someone here on the bolt narrow a big Dana rear for a '46 or so 1-1/2 ton just last winter or spring? Might try a search under "Big Bolts".
