Just replaced the headlight unit and everything seems to be functioning fine. However, we noticed a total of three bulbs and we cannot figure out the purpose of one of them. It is a very small bulb that sticks through the HID housing. This bulb is missing (bird took it out) but everything still seems to be functioning fine without it (HID lowbeam, non-HID highbeam, and the DRL). So what is this mystery third bulb for?

 

I forget the exact name but its a small park/accessory bulb that's on when the headlights are off.

 

Update as requested:

Installed the new headlight unit over the weekend. Took about 20-30 minutes total (with the help of a very mechanically-inclined friend). The fit seems to be very good and there were no real issues swapping out the headlight unit. It did not come with a ballast unit or bulbs. However, the ballast unit and bulbs from the old headlight unit were easily swapped to the new headlight unit and disconnecting and reconnecting the wires from the car to the new headlight unit were not a problem either.

So far, I would definitely recommend this particular headlight unit replacement part.

Now the only problem is that the new headlight looks so good compared to the other headlight (which is probably original to the car -- 16 years old) that I'm really thinking about spending another $200 to replace it as well (as opposed to just having it professionally polished, etc).

 

you can change the lens only with aftermarket headlights lens.
check my old post below
https://www.clublexus.com/forums/ls4...os-inside.html

 

I doubt the OP wants to go that route.

 

Would you mind elaborating a bit more on your thoughts regarding replacing just the lens?

 

Go to the link he posted. He created a DIY.

 

In going to five these headlights a try also. I have new corner lights and it looks weird with the old dull headlights. I polished them with the kit that Kansas suggested but now they are so again, plus I don't feel like having to keep polishing them.