Hi-I just finished restoring a 1936 LeBaron coupe and had a duplicate casting made in stainless of the very nice replated original gas cap for another 36 LeBaron coupe owner.
I used an engine sand casting plug modified to match my Lincoln's original to make a new 3 pronged retaining cam and a spring brass backer washer from an early Ford gas cap or rad cap kit to back the rubber gasket.
I'm a restorer and my customer car has been completed and shown 3 times this last Summer and is now with the owner.
Jerry Verdone made the casting and might still have the mold. contact at 717-949-3341 for info on the 36 Lincoln K gas cap casting.
I'd need to see any original cap again to see the details on the screw on internal parts.
I also made cast plastic duplicates of the door lock knobs and sleeves and the shifter knob. I hand figured the knobs to try to get an approximate look of the original tortoise shell originals.These are items I still have extras if you need.
Martin Lum
marty@oldercar.com