For models up to 1972 starting with 1969, the working procedure starts with the removal of the license plate and back-up lamps. Then, if there is any valance panel to the blower housing, it should be taken off. In order not to lose the alignment during the re-assembly, scribe around those bolts, then go on to unscrew the mounting bolts then lower the bumper to the floor. As for the models built starting with 1973, the procedure of disassembly and assembly is analogous to that of the front bumper with the only difference of the energy-absorbing component.