Tony -

I'm going by the original '68 & '69 Decor Group Road Runners I've had, which were all St. Louis cars.
My '69s had a little chunkier medallion style than my '68s.
Most folks wouldn't notice, and I'm not bustin' your stones, just passing the info I've experienced.
Yeah, the backing plates were pretty big, and the push-on nature made 'em difficult to swap over to new covers.