The Tacoma TRD elocker differential is the same size as the pre-Tacoma rear diff - the common 8" diff. The non-TRD Tacoma rear diff is 8.4", no real compatibility with the pre-Taco trucks.

On the front, I'm not entirely sure. Pre-Taco and Taco both have a 7.5" front diff, but it was redesigned for the Tacoma. I *assume* the carriers are different, which is what matters. Perhaps someone who's opened them up can elaborate?

4x4Wire's Toyota Section
1995 FZJ80 LandCruiser - 3 locking diffs, +200k mi, JD HIR's, 285/75R16 Nitto TG's
Olde North State Cruisers