K frame confusion

Mother mopar sometimes carried over items slowly, and used up remaining 72 Parts in the 73 , have seen it many times on other cars and years , my 72 challenger has some 71 dash components and some other interior items that were specific to a 71 not the 72 , so best guess is thats what happened since 73 was the cross over year ,,other than that maybe someone else did something to the 73 you pulled it from