BS is 7.25" up through the late 90's. After that there may be some variation on the civilian models. 12 bolt radial units are the only way to go.
In Process: 91 Wagoneer, D61/71 axles with 3.07 gearing, NV4500, NP205. Cummins 6BT.
Back burner project: Crew cab M715, Cummins/Allison/Rockwell Tcase/Dana 61/Dana 71.