Parking Brake Strut

[truckster]

I had a metallic sound coming from the rear of my truck after I crossed some railroad tracks today. I went straight home and pulled the wheel and drum, and this is what I found.

I put it back together without the strut, as I don't really use the parking brake very often, but I'd like to have it if I need it. I looked through a number of threads and Dorman 21149 looks to be the part everyone says it needs. The online parts catalogs all list it as the correct part for basically 60s to mid-80s GM 1/2 and 3/4 ton C and K pickups, but they all say it doesn't fit the Blazer. Is it possible the Blazer used different rear brakes, or is the information just missing from the parts catalogs?

Also, would any of you know the part number for the spring?

Thanks.