I have a '93 Taurus with 160,000 miles that I've had for a year. Coming home one night from work, in heavy rain, both headlights went out.
When I investigated, I found that both headlight housings had water in them, and both halogen bulbs had shattered. The bulbs were dated "93" (!), so apparently both housings only recently started leaking.
I want to avoid spending $100 for new housings. I've Googled, and found a few recommendations of drilling a drain hole in the bottom of the headlight housing. Has anyone had good results with this?