If you are a fairly good scrounge and can do your own fabrication work, you can build a reasonably priced Dana 60 assembly.

This combination is easy:

Core 3/4 ton truck Dana 60 (ie. 4.10 open) $150
DoctorDiff 35 spline axle package (most lengths, assembled) $300
DoctorDiff 35 spline spool $125
DoctorDiff forged steel 1350 U-bolt yoke pkg $70
Pair, Koyo spool bearings/races $65
Carrier shim pack $10
Pair, Strange Engineering housing ends $70
Set, housing end T-bolts $25
Pair, spring perches $15
Pinion seal $10

TOTAL $840 (plus parts shipping)