GM moved the location of the headlights in 71. When they did this the bolt that holds down the fender to the rad support needed to be moved up to allow clearance for the headlight which was now directly under this bolt. They stepped up the rad support and fender for clearance. As a result the 1970 fenders, rad support and, fender extensions are all for that year only.   The 72 has the same headlight location as 71 but there were further changes to the rad support to accommodate the turn signal