Great product , this is the second rail kit I've purchased, so my 18k super glide 5th wheel hitch can be easily swapped between my two trucks. Was not easy to install frame bolts on my 06 gmc 2500hd for the frame brackets . And nearly impossible to torque the carriage bolts from under neith to fasten the outside rails through the box to the frame brackets. ( I removed the carriage bolts provided and swapped them for a 3/4" grade 8 bolts with hex heads ) so they could be easly torqued and fastened properly. Also in the future if you have to remove your truck box you can do it with easy.