If someone can pick up that 6.0 and hold on to it for a few years for me I'll gladly come take it off your hands in early 2017.
For what you can get a RTR (ready to run) package from several companies, not to mention warranty, lower miles, NEW not rebuilt harness, tuned PCM and the support.....even the prices in that craigslist add are not good.....for example a RTR 350hp, less than 75K LQ9 6.0 with new harness, PCM with your spec tune ect...$3500-4K out the door. By the time you buy that 6.0 for $1200, the headache of re-working a harness, or buying a new one, sending the PCM out for tune, and all the misc. BS, trust me having one show up on a pallet ready to go can't be beat!!
To me, the warranty and support was the biggest factor....My warranty doesn't start until the 1st day I fire my engine up, and out of good faith call them to tell them I have it going!! Pretty awesome for a take-out engine! As an example, I bought the fancy racing/offroad oil pan ($450)! I have had my engine on a pallet for 6 months now and had never looked at what was underneath the shrinkwrap. A month ago when I finally unpackaged everything I found my fancy oil pan was crushed due to load shifting on the pallet. I called them, and had a new pan in 2 days, all I had to do was ship old one back!! They could have to me to pound sand.....I received it 6 months before!
And for the 5.3 guys RTR packages are $2500 all day!!!