trim piece

Hi there- I bought a replacement for my missing rear quarter panel trim (75605-60050) on eBay. It’s missing one of the fittings that the plastic clip heads attach to (see photos). Curious if anyone knows if the attachment has a part number or where I might find a replacement? I can’t seem to...

Shamelessly stole this photo from here on Mud because I can't find a better one: I'm looking for a pair of these. Color doesn't matter, but if you have brown that's even better.