6 volt bulbs
 

A friend gave me a cool old driving light....I'm thinking about mounting it on my F-1.
My question is, what is the brightest single filament small bulb made? This is a bulb like you would use in a tail light. It currently has a #87 bulb which is fairly bright, just wondering if some other type bulb exists. An LED bulb won't fit in the housing.....

Thanks.
The spark plug is for size comparison...

The # 87 has a BA15s base same as a 1156. You might check this site at the reference and tech section and see if there's something you can use differently-
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