Attached are some photos.

 

Type in Einstyn Wagon parts, on the web. He reproduces almost all GM station wagon rubber parts, he is the only one I know of, it looks like her carries these on his site. Good Luck

 

Yeah, I had sent Pete an email earlier for some other parts, though I don't see this particular piece on his site. When he get's back to me I will also enquire if he has them or a used one

 

No one to my knowledge is reproducing this item as of yet. Steele Rubber reproduces the other tailgate rubber/step inserts. You may be able to breath some new life into your old one with spray black Plastidip available at most stores or Amazon.