I've got the 'optional' clear taillight from MINI on my vehicle at the moment. I hate them but they came with the car. I have found someone locally that is willing to swap with me for his regular lights. The question is that I have the rear fog option and he does not...does this matter? Is there something special about the taillights with rear fog or is it just an added bulb that I could do to his lights?

 

You need to be careful when swapping taillights in the first-gen Minis. They fooled around a lot over the years with the placement of the reverse lights and fog lights.

For example, my 05 has white reverse lights tucked into the lower inside corners of the tails (see first picture). Your 04 might have the reverse light in the bumper (see second picture). The wiring is different I think, so you might have trouble swapping one for the other.

 

http://www.images.gominigo.com/INSTR...ly2005_BLK.pdf

http://www.images.gominigo.com/INSTR..._02-04_BLK.pdf

http://www.images.gominigo.com/INSTR...5-2006_BLK.pdf

 

Sorry, maybe I should have mentioned this. I have a 2004 as well as the other owner. I'm aware of the taillight change but ours are the same.

The other thing is that my rear fog light is in the taillights, not below on the bumper. Will there be a problem adding a bulb on his for the rear fog?

 

Note that those instructions require you to have the bumper-mounted light module. My 05 vert, for example, just has a plastic blank in that spot, so I'd need to find one in order to use tails that don't have a reverse light.

 

You should be fine.
The '04 fog light in the tail lights were in all of the cars, but only the ones with the option activated work. Many of us have even used a jumper to have the fogs come on with the brake lights.
I have an 04 and lights are there so if you have the rear fogs option you should be able to just plug in the new (original) lights and have the rear fogs.

 

If both of you have 2004's, the taillights are a direct swap -- nothing else you need to do. The taillight is supplied from the factory with a rear fog bulb in the socket even if you don't have the rear fog option.

 

Thats what I like to hear.