I just found this thread and one thing stood out, I know for a fact I was able to remove 11" drum brakes from a 1969 8 3/4" axle housing and bolt them up with no mods to a 1990s 8 1/4" housing out of a Jeep Cherokee XJ. Only difference was the 8 1/4" housing had one less bolt on each side at the tube flange. I put that whole setup in a 1988 Chrysler M-body to upgrade from the 7 1/4" with those atrocious 2.21 gears, all dropped right in!
Older Grand Cherokees are all over the place here in junkyards and for sale, Colorado is Jeep land.