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On my 78 I replaced the dash with one I bought from a member here. It had a small ding in one corner but I am not sure if it was OEM or aftermarket. I kept the old one on the bench and put the new one up against it. Lots of screws in the back side for glove box, interior lights etc. Put as much together as you can before putting in place. Especially the glove box. I had a thread somewhere on here where I described how to get the glove box door straight. Fro my experience there is enough WIGGLE ROOM that I think an aftermarket one from a reputable vendor should work for you. No matter what you get, getting it into place isn't going to be easy with or without the windshield in place. It made no difference for me. The corners on mine had two slight score lines in them, diagonally across. I tried not to bend things over, but once I saw those lines and figured what they were for it was a piece of cake. I put one side in, then on the opposite side of the dash I bent the corner down just enough to get it in place past the A pillar. Once installed you don't even notice that little bend, as if it was designed that way. OEM or aftermarket, I don't know but it works. Just take your time and try and plan out anything else you might want to do, WHILE YOU ARE THERE...