There are also some cosmetic stylings that are not definitive proof, because they are easy to change, and not of use if they are not there.

6 cylinder: holes in rear lower front fenders. 3 emblem holes on flat hood. Engine mounts for a 6 are different than an 8.

V-8 except 400: flat hood with 2 emblem holes, no holes in lower rear fenders.

400: Hood with twin bulges, grilles with additional chrome trim bars along centerline, 400 emblems on hood and deck lid, arrowhead badge on front bumper.

Again, as these items are readily changed, they are not definitive.