The Lens Retainer Bezel was used on all 64 1/2-73 Mustangs. The Lens itself will be either a 64-68 version or a 69-73 version. Although both versions had the same number molded into the glass, i have found that the earlier lens has a longer end one side with a 'forked' end for the retainer screw to go through. the later lens was cut off on that end with no need for a 'fork'.
Both the Bezel and the Lens were also used on most other Ford-Mercury products within that time period. The Main part of the license light(housing with electrical socket) is the differentiating factor on what model the license light is correct for.