@IaM-Ray I used a spare tire anchor from a Cadillac but it's the same for any GM product with a spare in the trunk - Just a threaded post with a hook on the bottom that fits through a holder bolted to the floor. There is a metal disk that threads onto the post and that holds the spare wheel in place, and then another disk that holds the molded plastic cover over the wheel to make it look nice. I deleted that cover, flip the spare over so the back side well is "up", drop the spare parts holder into the well and use the disks to hold everything in place.
Don't know whassup with that photo - Looks like it got squashed or something but you get the idea.