From what I've seen, GM would have been smarter to put the rear disc callipers at the back side of the axle, instead of the front. Sitting at the front side, they are wide open to rocks and mud. They often get rocks between the calliper and the rim and cause problems. The brake hose is exposed where it bolts to the calliper and often rocks hitting the banjo bolt will loosen the bolt and it starts leaking brake fluid. We can and do install special guards that help to protect the callipers a bit from rocks and mud. But it would have been better to have them at the rear. We had a new Ford truck in the shop the other day, and it had the callipers positioned at the rear side of the axle. Much better.
Ian