The TDI would be nice but it would seem to me a larger NA engine would better suit the yota. I'm sure the 44mpg will quickly turn into low 30s in a small truck. Not that is wouldn't be worth doing or even really cool.

(aka suprathepeg, aka Sean)
89 v6 SWB truck "BLACK BEAUTY" EB valves, P&P head 30 over.
95 FZJ80. Lifted. locked and rollin on 33s (my dream machine)