Well no matter what you do, you are going to have to mess with a pretty good amount of wiring, because you hae to use an engine newer than your truck to keep it smog legal. What year 4runner do you have? Seems like the 3.4 v6 swap is pretty common in the 4runners. I have a 7mgte swap done on my 87 4runner, but I also dont have to worry about smog. 3rz swap seems to be pretty common these days too, and of course there is always the Vortec 4.3 v6 which is nice because it fits better than a v8 but still has alot of power. Lots of options, but all of the above options require extensive re-wiring or an expensive pre-made harness.
