Let me guess, front driver's side marker light? Happened to mine, I think it's from the excess heat on that side of the engine (the check valve on the air rail failed, p.o. never fixed it, leaking hot exhaust for who knows how long). The whole plastic housing for the light crumbled.
Of course, it happened as I was checking out my frayed harness leading to my headlight, which had decided not to work (wire insulation was brittle, probably from the heat, too). And the marker light didn't just crumble, the leads touched each other, shorting out and blowing the fuse, which also controls the tail lights. And it was New Year's Day, in the evening, and I had 60 miles to drive home. With my wife and two kids in the car. Did I mention I didn't have any spare fuses?
After some real white-knuckle driving on the highway, I pulled into a gas station that had fuses for sale--bought a whole bunch of 'em.
Popped the fuse in, then realized that I was only missing my low beams, and drove home looking like the space ship from Close Encounters.
Oh, and in case your wondering, I think the marker light is sold as one piece only, no cheap replacement bulb. :-[
