On a recent trip, a rock broke the lens on one of our running lights (switch on dash calls it Aux HD Lights). I was unable to find an exact replacement, but found lights that worked nicely from Northern Tools. It is their item number 18814-1301 (3 1/2 Halogen Driving Spotlights -- $12.99 for pair). Their URL is NorthernTool.com.
The OEM light is 4 inch dia. The replacement light fit without any modifications and looked good.