Demco 8551002 Hijacker UMS-Series Under Bed Mounting Bracket Kit - Chevy/GMC '11-'13 UMS Series uses no visible bed rails Mounts to brackets underneath the truck box Requires only four holes for the mounting pins to attach the hitch securely to the brackets underneath Fits 2011-2014 Silverado/Sierra 2500 and 3500 HD, 6.5 box only