You know that spring clip/retainer on your sunroof wind deflector (the one that cannot be found at the dealership). Here is the part # 99979958 Spring, Sun roof part can be found at https://gmpartsheadquarters.com for under $10.00 us
I believe he might have made a typo, and the part was 88979958
http://www.wholesalegmpartsonline.com/products/Chevrolet/SPRING-Sun-Roof/3097537/88979958.html