The auto trans doesn't really care too much about the transfer case. You just make sure the truck you buy has a speed sensor on the transmission output shaft. I think in 2004 they got rid of that sensor since all the 2004 tacos had abs, so they just used the ABS speed sensors, which you won't have once you swap the axles.
Pretty sure you should be good to just buy a transfer case and inchworm? advanced adapters? maybe makes the 2-4wd adapter. Or just get a used complete auto trans with the transfer.
Or go big with an atlas...
Wait, the tacomas are drivers drop transfer case, so you need to figure that out.