Re: 9006 and 9005 bulbs are they the same?
Other than the wattage being different (9006 are 55w, 9005 are 65w), if you hold the 2 bulbs up side by side, you will see the surrounding tabs are a little different. This is so you don't put the "wrong bulb" in the "wrong" socket. But since the tabs are plastic, you can use a file to ground down the plastic on the bulb, or even some wire cutters to snip the plastic.
With about 2 minutes of work, you can make either bulb fit in either socket.
My experience is with the regular halogen bulbs. I am assuming the HID's are the same.
2003 Chevy Tahoe