2000 sierra engine and tranny swap

[chevroletman223]

Ive got a 2000 sierra short step 4x4. it has a 4.3l and a nv3500 5spd, i absolutely love the truck and dont want to get rid of it as its paid for and i love the looks of it, but id like to have a little more power and as i get older im getting tired of shifting. So i was thinking of dropping in a 5.3l and a auto trans from a donor truck at the local scrapyard thats got really cheap engines ($100). Does anyone know the extensiveness to this swap? i know id need the engine and its accesories, the trans, the transfer case, the engine wiring harness, steering column, gauges, engine mounts, radiator, computer, and i plan on putting electric fans and custom exhaust in. Is there anything else? if i convert to an automatic can i still use my under dash wiring harness? driveshaft? will there be any problems with bolting an auto tranny and transfer case up to my frame? Thanks for any and all help guys, i already know its a big job and ive definatly got the ability to do it, ive built countless cars and engines. Just need to know the extensiveness.