2004 Double Cab Prerunner 2.7L 3RZ-FE 2WD to 4WD Conversion

Hi, I am new here. I've looked through many of these posts and can't find the exact answer I am looking for. I am interested in converting my 6 lug 2WD Prerunner to 4WD. I am currently researching and trying to find the parts I need to do so and am looking for advice on this project.

I know that the 04 double cab prerunner came out with an automatic transmission, which from my vehicle information is a B04A/A340E. I can't find anywhere what transmission I need for the same engine but for 4WD. I know there are other things I'll need like front axil differential and the transfer case. Other than those I still need to figure out what I need to buy and what parts I need.

Are both Manual and automatic an option? or if I go through with this conversion is only one of the options available. I know enough about vehicles to work on them, I don't know enough about what I am doing without extensive research. Is there anyone else who has done this before with this exact make and model? Is it the same process for older 1st gens? I understand that the 3rd gen 4runners are compatible with 1st gen tacos, will I be able to use one of those transmissions instead?

If anyone knows the details for these questions that would be really appreciated. Currently I am doing my best surfing the web trying to find out the exact model of transmissions and what not and which one would be the best. I am getting a lot of mixed information on the web and can't find an exact answer for the many questions I have. I just want to make sure I can do it right and have all the right parts before hand.

Thanks again for anyone who is willing to help me out.