Yes it's possible, but why? You would basically need to find all the 6.0l engine parts, accesories, ac hoses, compressor, air intake, exhaust, wiring, mounts, and such for your burb. Then swap all that onto a 5.3l to get it all in. Then have a custom tune flashed into your pcm and possibly have to change tac modules to work with the different throttle body. And when its said and done you will have taken a HUGE hit in power. Thats not counting regearing as you WILL want 4.10's with that small an engine in that big a vehicle, and I believe you currently have 3.73's.