i'm confused about this 5.3 swap

ok heres the deal I have a bad transmission in my 96 gmc 2wd 5.0/auto truck. I have found a 5.3/auto 2wd out of a 03 chevy pickup that I could purchase cheaper than rebuilding my trans for.
So my question if I recieved the engine/tranny complete wiring, accessories etc, wouldn't all I need is the mounts for the lsx type engine and swap this in? Or would I have to get wiring dedicated just for the engine/tranny for the swap?
Any input would be appreciated. I'm not looking for anything performance just a factory to newer factory swap.

You'll need a dedicated wiring harness for the engine and trans, a PCM, tuning, exhaust mods, mounts, and misc parts that add up to be quite a bit.

2003 5.3 will be DBW so you will need all the equipment for DBW.. (peddle, tac ect...) or convert to DBC...:)

the engine/tranny will have all wiring and pcm so I'm assuming I could use it without going aftermarker right?
I'm used to swapping carb engines sorry for the newbie questions.
thanks again for the responses

Yes the stock harness will work but you'll have to graft the old vortec harness into it and add a couple of things. Allen has a real nice harness and it's stealth. I'm thinking about pulling mine out and sending it to him so he can build me a few plug and play vortec harnesses.

thanks