One of the tail/brake lights on my Model T hauling trailer went out and I need to find replacement. I need a low profile 12V, double contact, double filament, bayonet style bulb with offset nibs. That is, the nib or pin on one side, needs to be higher than the nib on the other side. I am looking for a low profile bulb because, as I was changing the bulb, I noticed that the higher profile bulb that came with the light, is too close to the red plastic lens and has started to melt it so I need something that is not so close to the lens. Here is a picture of what I need. Notice the offset nibs on each side. I have been able to locate low profile bulbs, but the nibs on all the ones I have found are even with eachother and not offset, so they will not fit into my socket properly, which has offset grooves into which the nibs fit and twist into. Thank you for any help you can provide. Jim Patrick.
These might work in your application.
Good luck with your project. Bill
Bill's suggestion look like the solution. You need the indexed pins to get the lamp oriented correctly. With non-indexed pins, (like the Model T Magneto headlight) you might have a bright taillight and a dim brake light / turn signal, depending on how you put the bulb in.
I have filed down the nib on one side to get bulbs to fit on occasion, one is enough to hold it in place. If oriented wrong it's easy to turn it right
Thank you Bill. I went there and ordered two. It appears that the nibs are offset to fit my socket. Thanks again. Jim Patrick
I have a '25 with an original taillight. Does anyone know Ford made two different styles of license plate/taillight assemblies? Well, they did. All I can figure out is the style I use was most likely developed after Model T production ended perhaps in the thirties. The bulb socket is straight through with nothing inside, and requires a spring loaded connector similar to the headlight plug which is a double contact. There are also single contact units. With this, I'm able to use one of Snyders Model A cowl light bulbs, but have to file off the offset pin to get it to fit. It works! This way, I have a running light, and a nice bright stoplight.
If you want to support a vendor, http://www.snydersantiqueauto.com/staggered-pins-turn-signal-bulb I used these bulbs when I converted the tail lamps on my 26 to tail, turn, brake lights. They were the only ones short enough to fit in the 26 tail light.
Just for those who want to look in catalogs for bulbs. The "correct" naming of the bases you are talking about is what you have actually called them namely BAYONET BASE for the one with pins that are across from each other and INDEXED BASE for the base that has one pin higher than the other. This naming applies to the large diameter typical older automotive bulbs. The dash lights used to be #47 type bulbs and those were called MINIATURE BAYONET base. So if you shop a bulb catalog the name BAYONET base will be the large fat base with pins across from each other and the name INDEXED base will be the large fat base with pins that are offset.