Proper cone for 418-8H Series II?

I have a pair of 418-8H Series II speakers that I need some advice on the cones installed in them. They were sold to me as NOS, unplayed, and seem to be just that. Compared to my 417-8H Series II, they roll off the highs quite a bit more, so I was wondering if the cones are the originals. They are stamped 21353-7, which is a valid Altec factory cone, but I'm only seeing comments about them as recones on a 421-H Series II or a 420-Y, so far. Are these cones correct for the 418s I have or are they more of a woofer only and not a full range cone?

A little more info: the 418-8H Series II speakers have no labels. They are just plain black stepped alnico magnets on the white frames, typical for OEM models.

Any help would be greatly appreciated!