On this Chevelle and similar GM A-body cars, five bolts secure the rear of each fender to the body shell. Shims can be placed between the fender and body at each of these locations. Shimming at location A will push the top of the fender outward horizontally. Adding shims at location B will raise the fender upward, and make the side profile (the fenders bulge) flatter. Similarly, shimming the two lower locations (D) lowers the fenders bottom edge and flattens the bulge. Playing with shims at location C changes the width of the fender-door gap, making it thinner (less shims) or wider (more shims). Nows a good time to make sure each door is aligned to the rear quarter-panel before you proceed.