I've been searching for theses clips that the factory used on the lower front shock mounting points and I thought I should share what I found. I found their twin brothers with SAE 5/16 threads,but I wanted the metric version GM # 15658213. The first thing I found was that the metric versions are only available from GM and can be found on a number of GM authorized on line sites. The lowest price from one of these sites is $2.80 each. Today,while searching for something else,I found them on a 4 wheeler site for $1.39 each in a 10 pack for $13.90.
https://www.wheelerfleet.com/product/nut-mount-shock/103313
https://www.wheelerfleet.com/product/nut-mount-shock/103313