The 1937-38 lens and stainless ring are fairly common, same with the larger and flatter 1939, but what does the 91A over 18 fit?
I never got into the late '30's Fords, there were a lot of standard and deluxe parts that were unique to the different models. A '37 stainless ring is too small to fit this lens. Hershey seams like it was months ago, it was another good one for me.
78 lens is for '37. 81A lens is for '38 and Standard '39. 91A lens is '39 Deluxe and Mercury. I am not sure about lenses for Lincoln Zephyr, may be same as Ford, not sure. 78 and 81A lenses are interchangeable, 91A lens won't interchange with anything else.
I won't blame anyone for not 'getting' the pathetic sense of humour in my previous post, but the 1938 Ford 7W range [four cylinder] used a mini version of the 1936 V8 headlamp lens.
I didn't know about the smaller British bug eye lenses. I put '36 car bug eyes on my '38 pickup. '35-'39 trucks use the same lens as '35 car, but the '36 lens will fit if you use the '36 retainer ring with it.