So I have finally gave up looking for that elusive 2 element bulb socket for the rear fogs that I would need to have the fogs act as clearance lamps as well as stop and signal lamps.

My question now is, once I decide which single function I wish to have (Running lamp only? Turn signal? Brake lamp?), can anyone please tell me which of the two prongs on the single element socket is for the ground wire and which one is for the positive 12v power?

I have looked at the socket and can't make heads or tails on this. On a single element bulb, is the bottom contact of the bulb for positive 12v power and the rest of the base for ground? Or is it the other way around. IF someone can answer this, I can then follow the contacts on the base to wire correctly.

Thanks

yes, the small contact in the middle is +12 ... but halogen bulbs (unlike LED's) are not polarity sensitive.

Just FYI, the existing rear fog wiring harness already has both lamps in parallel, so if you inject a +12 volt feed into the circuit, for example from your brake lights or reverse lights, they both light up.

Also they have the same wattage as brakelights so if you wire them as running lights then they will be too bright and it'll look stupid and annoying, like people who drive around in their German with the rear fog light on.