I don’t believe the center spoiler of a 78 will fit 79-81 actually. Luke would probably know better than be and I sold my spare 79 spoiler I had but I have a 79-81 nose and crash bar which are both different than the 77/78 nose/crash bar and I’m pretty sure the 79-81 center spoiler attaches to the crash bar whereas my 77 does not. It has tabs that stick out and go into spots in the bottom of the bumper cover. So, I could be wrong but I don’t think it will work.