88 shift on the fly?

i was wondering if a 88 toyota 3.0 4sp 4x4 was shift on the fly 4wd.

Only if you like grinding gears.

So, what is the rule on shift on the fly? On my '90 22re I can shift between 2 and 4 hi on the fly. Obviously not into low range without being stopped, but I didn't think that I should be able to shift between 2 and 4 hi. Anyone?