The rails are all interchangable. If it is a picky restoration then you would need to weld some holes shut in the 72-74 rails. The inner fenders are all interchangable also. The 1970 inner fender is different than the others. The 71 is close to the 1972-1974 with some holes and factory tapped mounting holes being different. The 1972 - 1974 again is slightly different than the 71. All will interchange though. Let me know if you need pics. I'll dig some up.