1996 4.3 vortec to 5.3 vortec swap. NEED HELP!!!!

[Opeddy]

So I know this might be worn out by now and I've done my fair share of research. But it seems there's just a couple things I can't figure out. Let me thank you for your time to read this. So earlier today my 250k mile 4.3 vortec decided to take shit. So instead of replacing or fixing what's wrong I'm just gonna swap the engines *dream come true here lol* so I found a guy selling his 2002 5.3 engine with 55k miles. It comes with a 4l60e tranny, all the engine accessories, wiring harness, and computer. My question here is can I use the wiring harness and computer in my truck? Will I have to rewire it? Or is it as simple as just putting in the new computer and wiring harness and taking out the old one. For some reason I've never been Blessed to find the exact info I need in this, or I've just been to blind to see it. Any help would be much appreciated. And if you have any other tips and tricks feel free to say them. I'm always eager to learn more!!!

[Chevydillan]

Is the 96 4.3 still throttle body?

[droopyzda1]

I did that swap last year to my 94 obs. you are only going to use a few wires from the obs harness to the 5.3 harness. Like power, ignition, fuel supply. Go to lt1swap.com and he has a step by step procedure including a chart of how to modify he LS harness and take out like 30 wires that u will not need. UR fuel pump should suffice. I had to uupgrade mine to 96-98 obs ccause the 94 doesn't throw enough pressure. I wired my stock obs gauges to the nbs harness and everything reads accurately.

Tips: U can use your original a/c compressor. Don't know what style u have but definitely doable. Can use the obs radiator. During the swap is a good time to upgrade to electric fans. One last thing, please do think it's a weekend swap and that's it. Plan to have thr truck out of commission for at least a month. It took me 7 months on and off to get the swap done. Then another 3 months on and off to fix some bugs.