My friend has a 2WD 96 Tacoma, we did a lot of research on what would fit best in his truck.
First of all, do not go with 2 12's. Second, not xplods.
We thought either 2 8's or 1 10" would be best, he ended up going with 1 10" because he lacked sufficient money for 2 nice 8's. Go with a sub that will give you good sound quality, because you'll hear all the imperfections in the bass with the sub sitting right behind your back if you get a lousy one.
RangerMan recommended we get either a eD 10kx or a new JL 10w0. He said he'd go with the eD over the JL. And he also said he'd only get the JL if it was brand new.
Hope that helps.