Rummaging through my stuff I found this set of rear WDT painted molded splash guards that I once tested on my Denali:
GM part number: 19212809
They were on for all of half an hour so they're in like new condition. I don't have the little screws that came with them but they are identical to the ones you have holding your liners so you can use those, that's how I installed them.
$50 shipped to L48.