If you had tapered 400 emblems , I think Jim is correct ,they probably used trunk emblems....I`ve never seen tapered hood emlems for 400, 350 yes, b/c less slope on hood = - scoops
so the 400 trunk emblems will have different holes , since left and right 400 emblems arent the same , nor do they have mirror image hole patterns... hood emblems slope/lean one way on left side , opposite slope/lean on right