Thanks for the replies.

Checked reflectalite.com and haven't found an equivalent to their GH157 in the U.S. The Road Toad bulb is the closest I've seen.

I like the idea of a LED conversion, but the all-plastic construction of the PreView Xe would probably make a swap problematic. For the cost of the bulb linked above I might be better off trying a cheap Cree AA flashlight.

I have 2 of these Specialized lights and they've held up well over the years. I'm still open to ideas for getting more life out of them.