My feeling was that if the bearing is spun, that the unit was likely subject to considerable abuse. I guess I could have the case magnafluxed and lock tite the new bearing on there, but I could also take my chances and buy another one with the hope of getting one in better shape.

Kary, which bearing flange is susceptable to the cracking? The case or the cover?

1994 3.0L 4x4 pickup.
4.62 gears (4.22 stock), 33x10.5 BFG MTs. LSD rear. Five speed trans. 172K
Previously owned Mitsubishis:
1986 2.6L 4x4 Mighty Max, 1985 2.6L 4x4 D50
1987 2.6L Raider, 1989 3.0L Raider
1995 Montero SR