I have a 70 front end on my 73, I didn't swap my fenders for 70 because I'm eliminating my side markers all together, also they make weld in conversion kits to swap the marker opening to 70-71 from 72-74, and the kits is cheap, a lot cheaper than swapping fenders or rear quarters. The tail panel is the biggest part, plenty of cutting and welding, and obviously different lights, all in all, it's a pretty pricey swap to make, but u can also get 72-74 challey's a lot cheaper than the 70-71s, I paid 5k for mine rust free driver, and already had the 70 grill with it