SPRINGS front springs are different in the 71 right spring is longer. Rear springs are the same. FRONT SPRINGS 71-73 24OZ Wire Size-----------.425 Spring Length------15 1/4" Right side, 14 3/4" Left side Spring Rate---------1OOlb REAR SPRINGS 71-73 24OZ Wire Size-----------.452 Spring Length------15" Both sides the same Rate-----------------13Olb FRONT SPRINGS 2+2 75Z wire size----------.458 Spring Length------15 3/8" Both the same Rate----------------145lb To check spring rate us a bathroom scale and a drill press. Put the spring holder on the too of the spring and a couple pieces of wood on the scale and put pressure till you hit 5Olbs on your scale then set the inch dial on the drill press to 1,2,or what ever then from the 5Olbs point apply one dial inch worth of pressure and what your scale reads will be your spring rate!