Who is using Grand Cherokee rear disc on 8 3/4

The Mopar Action article was photographed and published on the forum. It uses tapered bearings, not Greens, though. It's designed for B/E-Body 8.75" axles, which have a different brake spacing than A-Bodies. It also also requires some modifications of the caliper bracket or custom axles

I believe adapting these brakes are much closer to a bolt on with 8.25" axles.

There are a few threads on FABO detailing member's swaps. Searching for these will turn up most answers OP is seeking.