Stumbled on these a few days ago. Dorman bubble pack. They were on the board, in the “Help” Hardware section of a Canadian Tire Store. Caught my eye as they are same size as our exhaust port hardware. Each stud has a small end that appears to take a 6 mm socket, to drive them in. They come with flange nuts, that are locking.
WARNING: when I got home, I was packing away the other stuff I bought and realized these items were hanging in the “stupidly priced, but you are desperate” Section. I will be returning them. Probably 1/3 the price at a local auto parts store......