The 70-73 Camaro clips have different frame horns at the front than the 74-81 clips. The 5mph bumper law mandated in '74 required the beefing up of the frame horns to support the shock absorbers that attached to the front bumper. These frames will work, but you have to get a little creative when it comes time to make the mounts for your stock 55-59 bumper. Everything else from the horns back is the same. The 68-72 Nova clip is the same as the 67-69 Camaro/Firebird clips. These are slightly narrower than the 70-81 clips and they have the steering box mounted behind the crossmember (rear steer) whereas the 70-81 clips have the box mounted forward of the crossmember (front steer). The only disadvantage of the Nova clips is that it can get very tight when you have to run the exhaust, and they never came with the massive sway bars that some of the 70-81 clips had (Z28 and Trans Am). The disc brake design is better on the 70-81s, too. Any of these clips will work just fine, but some are better than others.
________
****