After pricing out various 8 3/4" axle components, and getting a bit of sticker shock, I'm wondering: How readily could one swap a 9 1/4" late model truck axle (Durango/Dakota) into our older cars?

Granted, you'd need custom axle shafts with a 5 bolt pattern (about $4-500), but the axle housing and gears are relatively plentiful and cheap. Furthermore, most of them came in very desirable gear ratios of 3.55 or 3.92 along with the Sure-Grip

Thoughts?