I put a set of those lower door skin panels on my 77. They fit both 3rd and 4th gen doors. As with any rust repair panel, they take a bit of trimming, test fitting, and minor re-bending to get a good fit. Also be prepared to deal with some rust damage to the lower part of the inner door structure as well. I had to weld a few homemade patch pieces to the lower/inner door structures on my 77 prior to installing the outer skin patches.