I have searched high and low, none exist.
Seeking interest in a group buy.
AASCO will engineer and produce a lot of 10.
A one-off will run about $2500, number based on a one-off they just made. 10 or more should get the number down below $250 each.
They can be produced in aluminum with replaceable friction plate or in steel.
Ring gears are available.
Looking for those of us who have keepers and are serious about keeping our MJ/XJs on the road.