I don't have any lights but there is a post on here on how 2 replace them for cheap. I did it and the lights work perfect. I think it costed like 15 bucks. Thats cheaper than buying a gm light. Trying to help, hope it did.
http://syclone.invisibill.net has a guide, as does http://www.sytyarchives.com on how to replace the foglights. When TookyCat's truck got hit, the whole foglight assembly from GM was $127. The Blazer foglights are under $20.