You should have a label on the bottom that tells you. It is most likely Texamatic 7045E. You will have a hard time finding it anywhere other than the dealer. But take my advice, save a bunch and just get some Dextron IIIg fluid. Read on other forums what cheaper fluid you can use. (you just need to replace it every 40kkm or so.)
That said, I hope this is for a transmission other than the dead one, since there is absolutely no chance new fluid will revive your box, sorry.