I suspect the reason you are having difficulty is b/c you aren’t referring to the part with the name the vendor’s parts database expects. This is a common problem with finding auto parts. “pigtail” is the usual name for that part as is used here. That’s probably the term you need to use. I expect a Chevy Dealership parts department would have it or could order it for you. Take your new headlight in with you, so you can double check it fits. There’s probably more than one Chevy model that uses that part btw. Did you check at your local pick and pulls? If not, just surf over to their website, and you can check what cars your local pick and pull have on their lot. They’ll have a cross reference of all models that use that part too, but you’ll have to go to one in person to get that list probably. Those folks at pick and pull in my area anyway are very friendly and helpful about stuff like that.
If you simply cant find that part an auto-electric tech could make you a work-around for not much $$$ I expect. They’d just use a different pair of connectors is all, replacing both the connector on your new ass’y and your car’s harness. I had a problem like that on my Corolla a couple years ago, with the license plate lamp wiring. The connector had broken. My solution: No replacement connector at all, I just soldered the appropriate wires together.