6. The front half of the subframe was then bolted in place. Pro-Comp has you drill four vertical holes into the truck's frame to support the new subframe. Again, by bolting the subframe into the old lower A-arm mounts, it can be used as a template to locate where the new holes need to be. With both the front and rear subframes in place, Corder then used a prybar and a screw jack to maneuver the lower A-arms into their new mounts, which are now 6 inches closer to the ground--hence the 6-inch lift. Once in place all of the bolts are installed and the nuts are left loose.