I received an answer from a friend of a friend who is a former Lincoln dealer. Here's what he said: Jim: Those "window glass" pieces are indeed for license plates. This kit is for the plastic covers only; they were intended to be used in conjunction with a set of Lincoln accessory license frame holders. The metal frame holds them in place. I'm told these were made in different sizes, as license plates were not uniform in size from state to state in those years. The different size kits have a different letter suffix for each size. Yours has no letter on the wrapper; maybe it was "size #1". California plates, for example, prior to the 1956 series were a larger size with rounded corners. So there were differences in plate sizes even within the same state based on vintage. The BH parts prefix number was first used in 1953, but these plate covers probably had an application spread for more than one year. The yellow and green wrapper was used through circa 1957. Those HDK kit part number prefixes were used around the mid-'50's. Gary S.