if not the lines. then check to see that you pan is in tact. (it's pretty thick, and I don't imagine that they damage easily) check around the pan. the bolts for those strip VERY easily. if someone has worked on the trans before, there may ba a chance of one or two bolts stripped. check the cover to your final drive (on your drivers side of the trans) make sure that nothing is leaking there. check where your axles go into the trans and see if anything is coming out.

check those cooling lines again. that and the pan would be the places that I would bet on.

we don't even want to get into what happens if you find fluid leaking from between your engine and trans (shudder).

keep that thing topped off until you find the leak. we don't want you blowing up that trans, do we?