If you have a V8 4Runner with the five-speed automatic, then it probably won't have a dipstick. It is a sealed unit filled with the "World Standard" (or something like that) fluid that costs an arm and a leg; so I don't think you are supposed to change it under normal driving conditions.
In 2005, Toyota installed this tranny in the V6 4Runner models as well. V6 4Runners in 2004 still had the "old" four-speed automatic. If memory serves me correctly, the V8 came with it beginning with the 2003 model year.