Try these guys:
custom HID conversions, HID kits, LED, CCFL specialists - retrosolutions
9007-2 has a halogen highbeam built into the lowbeam HID bulb. The halogen bulb will be useless compared to the output of the HID:
9007-2 hid - Bing Images
9007-3 has the bulb either tilt or retract a little into the base of the bulb using a solenoid. This ensures that the position of the lightsource of the HID bulb matches that of the filament of the OEM halogen bulb. I've heard that these bulbs are either REALLY good or REALLY bad depending on the manufacturer.
9007-3 hid - Bing Images