OER Parts offers a wide selection of Brake Components for your 2004 GMC All Models. OER Parts offers 2004 GMC All Models Master Cylinders Components 2004 GMC All Models Master Cylinders, 2004 GMC All Models Bails, 2004 GMC All Models Covers, 2004 GMC All Models Push Rods, and 2004 GMC All Models Rebuild Kits and Parts.