I installed this kit on my 1988 C1500 a few months ago. It works well when paired with the smaller brakes on the 88-91 trucks. The stock parking brake cables were easy to modify and connect. I used parts from a different rear disc brake conversion kit vendor (that are included in their kit) to make the parking brake cables work and to mount the hardline/softline connection to the axle.
The Good: Very nice quality brackets and hardware. The rotors have the centers coated. The instructions are thorough with clear pictures until they leave you hanging. The mustang style calipers are easy to adjust.
The Bad: These are marketed as 12" brakes, but they're not really 12" (they're re-drilled 11.61" Impala SS rotors). The mustang style calipers are much smaller than the Cadillac calipers included in some other kits. The instructions leave the actual hydraulic connection up to your imagination. The included brackets/clamp to mount the the hardline/softline connection to the axle won't work on a C1500 axle.
Verdict: If you have 88-91 truck with the stock front brakes, and you want to avoid the Cadillac style parking brake calipers, and you don't mind spending extra time/money to make it all work when the instructions leave you hanging, then this might be the rear disc brake kit for you. It does work well on my 1988. If all of the above don't apply to you, you might be better served by one of the other brake kits on this site.