First of all anything is possible with enough money, time and space.
Next the way you make it sound, you think it is a possible simple bolt on swap. Toss a few springs and a front diff and it is setup, sorry it is not that easy.
The frames are not the same, the brackets are not the same. To use stock setup you will need tons of cutting tons of welding.
The easiest way is to sell the 2wd and buy a 4wd. But if your dead set on a 4wd swap, then you got 2 options.
1. SAS Solid Axle swap, cut off all suspension and steering system on the front end and CUSTOM make all the suspension and steering and brake systems. Get a driver side axle drop and 4wd transmission and transfercase. I did this swap on my 4wd check my signature.
2. Do a frame swap, get a COMPLETE 4wd frame. That is what I did to convert my 2wd to 4wd way before my SAS. It has to be the same body as yours, like single cab or club cab, short bed or long bed, same engine. Put your body and bed on top of the 4wd bed, keep your engine or use what is on there. This will be your best bet for a bolt on kit, a little tweaking may be needed. If you go this route a wrecked body but good frame is you best bet, or if you can find one with a dead engine and just use yours. I have a link in the FAQ.