Turn signal hood bulb retainer

On some CS cars as well as run of the mill 68 Mustangs I have noticed that there can be a little retainer in the shape of a "fork" holding the bulb and socket in the pot metal light assembly for the turn signal indicator light in the hood. I have no picture - sorry - but am unable to post an image anyway. Hope this is not too confusing, but could you guys and gals look under your hood and see if your car has a retainer held in with a little tiny screw that keeps the bulb socket from falling out of the light? Maybe one of you who has this feature will be kind enough to post an image on this forum. Trying to figure out when this retainer was used and make some sense out of seeing it only on some cars. You can also look carefully at the little hole in the light assembly and if you see thread marks cut in the metal your car at one time had these. If we get an image from someone this will bll be more understandable. Trying to get a handle on this little detail and sure need your help. Thanks!