Today I pulled out the starter and as suspected the contacts were heavily worn. As Mike warned in his instructions removing the plastic plug on the starter was a pain and ultimately it took me under the truck pushing the clip and a friend pulling the wire from the wheel well. The good news was that the two starter bolts were not corroded at all and were really easy to remove. The really weird thing was that the plastic cover over the terminal had broken down and turned in to a sticky goop which a pain to clean off.
I've read that all autos have the 1.8kw starter and manuals have the 1.4kw starter. My 2000 4runner 5spd has Toyota part number 28100-62050 which is the 1.4kw so this seems to be true.
Now it's time to buy some replacement parts...
- Matt