Mainly just took measurements from common points and only replaced the fronts one piece at a time. I traced the frame rail with a red marker onto original inner fenders, measured the front in a "X" pattern, drilled out the spot welds and left the old inner fender in. Then removed the rail then installed the new rail using self tapping screws until it was all lined up. After I replaced the rail I replaced the inner fender. I kept as much stuff intact as possible then I moved to the other side. As for the rear I just took some measurements from common points, but knowing I have the old floor pan to relate back to.
