Help finding a light socket

I bought some aftermarket blinkers that I like the size and shape of, however they are single-filament bulbs. I have some room to work in them, so I am considering two options... 1) I can drill out the formed socket and replace it with something for a dual-filament bulb. 2) I can add some LED's as running lights.

#2 is probably an easier solution to fabricate, but #1 may be a better long-term solution. The problem right now is that I'm not too familiar with light bulb sockets, so I could use some help identifying what the dual-filament version would be. The existing bulb is labeled as (E8) 3A9. If anyone can point me to the right socket style, and/or link me to any good sites that carry replacement sockets, I would appreciate it.

I could not find a bulb with that label on it. Is there anything else? Is it a standard diameter base>

It is stamped as a 12V 10W bulb. The base appears to be about 9/16" or 14mm in diameter, and is the type with pins on opposing sides, where you push it down into the socket and give it a quarter turn to lock it in place. Essentially it is a smaller version of the bulbs used in the stock turn signals.

That would be a "Bayonet" type socket. Sounds like a specialty item. Have you tried the auto parts stores? Some have an extensive electrical dept.
Here's a place to try: www.easternbeaver.com if they don't have what you need, maybe they know who can get the sockets for you.