1) 86 and back starion (and flat side 87s) diffs fit the front 7.5 truck carriers but require shims.
2) 88/89 starion diffs fit the 8 truck carriers.
3) 87 wide body diffs fit the 8 truck carrier but accept the 7.5 axles.
*If any of the above is incorrect, correct me before I start buying parts. Thanks

So mag00, 1) is what your describing?

And for me the simplest and cheapest thing would be to swap in a v6 8inch and do 3)

88 Montero, StarQuest turbo, Kormex 5speed +tuff-pan w/phoenix f. stage2 clutch, 4in lift+33' tires, 4.875 lsd, short-throw shifter, Aisin hubs, SR big brakes, gen2 uca's, elantra alt, and so much more... 16g turbo w/hardpipes + 4.90 locking disk-brake axle soon (maybe lsd or aussie front??)