The rear axle components in an LJ/KZJ are similar to those from a V6 4Runner or turbo Hilux Surf. The auto transmission is similar to one from a late 80-series, and the manual is the same as those used in both the V6 4Runners and later HZJ7x cruisers. The front axle components are shared with post-1990 70-Series and 80-Series cruisers. Transfer case is the same as a 60 or 70-Series. Frame is essentially the same as a HZJ77, but with different suspension mounts for the coils. IMO the only weakness you’d find is if you tried to push loads of V8 power through the diffs.