hi gang, got a question about my friends o3 Silverado. the rear brakes wear out much faster than the front brakes.they are drum brakes. no sticking brake lines or anything we can figure out. dealer has no answers either, any ideas would be helpful. thanks,!

 

Sounds like an adjuster. But I am not sure about.

 

which drum brake option does it have: 2 shoe hold down pins or the one big circular spring?