Yes sir, I understand. Sounds like you got it all figured out. The listings I bought mine from both said the lights had been tested and they accepted returns. Not sure how they would have done that or if they really were, but it made me feel a little better about giving them a shot without fear of being stuck with a headlight that didn't work. Post some pics when you get done!
I just finished doing this to my truck last weekend. I picked up the LED headlights from Ebay also. One was new and the other one used. The headlights are sealed units with all bulbs included. With the appropriate harness, they are plug and play.
When looking for 2016 headlights to possibly purchase to install on my 2015, I am seeing many headlights advertised as "GMC SIERRA 1500 DENALI 2016 16 LH LED OEM HEADLIGHT LAMP ASSEMBLY 1424" or similar that have a chrome housing on the inside instead of black. I think i like them but i can't find a single pic on the internet with these exact lights in them. Does anyone know what model these actually come in? Or am I missing something?