Welcome to the Nation. My research under transmission and engine hasn't yet yielded any clues. I don't know if it has any purpose except to hide the oil pan bolts and frustrate mechanics. Somebody else here may have a clue.
Your best bet would be a GM Dealer. They have access to more detailed parts information. Just show them the picture and tell them where it is located on the truck. Give them the VIN. Let us know what you find out.I took it to 3 different auto parts places because as your van see it's mangl. Google lens don't even know and none of the other google search have yielded positive results.