Properly align your 1968-1972 Chevrolet Chevy II / Nova body and front sheet metal with this Subframe to Body Shim Kit. These shims are required to achieve the proper core support-to-firewall alignment when installing and aligning the front fenders. Without the correct shims in place, the subframe can sit too high or become "wedged" upward, making proper fender alignment difficult or impossible. Installing the correct shims helps position the subframe at the proper height and allows the core support, firewall, fenders, hood, and surrounding sheet metal to align correctly.