Truck-Lite 10704 3" Grommet Mounts For 2-1/2" Lamps
I have used these on my roll bar the are for truck headlights, just cut out the inside and use some silicon they are pliable so they fit on the body nicely
You can find them without the stamping on the rubber.
http://www.jhtt.com/image/cache/data...04-800x600.jpg