I've installed 3 of the OEM fog kits using the "round style" glass lens. The housing is small, and perfect for 55W H3 bulbs. The reflector is EXCELLENT for halogen usage, but completely unuseable with HID bulbs (the round one is not even a halogen projector, but looks like one).
My OEM's are sealed in back with vents built in a "drip loop" fashion to keep them dry...you can get water in that area behind the Ody's "chin" on wet days, I've checked this. Affixing an HID bulb would be impossible on the round lens version, and you want to keep the setup dry.
"OEM style" fogs (clear or yellow) with the full form-fitting housing & lens is available for cheap on ebay, but you will melt these with HID bulbs...the HID gas capsule ends up very close to the lens, and well forward of the light source focal point. You won't get light where you need it. Also, it will get wet back there on a rainy day, whether or not you use "OEM style" or true OEM.
Best solution might be to get a projector with a true metallic cutoff shield, and install washers to pull the HID bulb aft to accomplish two things:
1.) Get the HID bulb arc capsule into the correct position.
2.) Get the HID bulb tip AWAY from the shield to prevent a short circuit (need a MINIMUM of 5mm clearance, maybe more).
It will be a bear to weather-proof this. Good luck.
OF