Slim LED Work Lights are MUCH cheaper nowadays.
IF THE IMAGE IS TOO SMALL, click it.
This mounting position will allow me to adjust them from inside the truck, and they'll work as cornering lamps or off-road lights. I'll wire them to relays & a switch so they come on automatically when the parking lights are on AND the t-case is in 4WD, or when I use the turn signals with the headlights on.
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To mount them, I drilled up from the outside where I wanted the bolt to go, and all the way thru the 2nd layer of plastic. Using that 2nd hole as a center, I hole-sawed an access hole in the mirror socket (visible in the lower L pane) for the nut & wrench. I made a simple steel reinforcement plate that slipped into the plastic head (while it was removed from the arm), installed the light's stainless bracket, and red-threadlocked the nut on when I had the tension set to hold the light where it's aimed. Then I drilled another smaller hole for the light's wire, and bolted the light on using more threadlocker. The wires are routed to the standard '96 Bronco 8-pin signal mirror connector, which has 3 unused positions.
The eBay price came down SUBSTANTIALLY after I bought mine (to ~$25/pr by 2016), and they're now available locally at Northern Tool for ~$50/pr. They're also available with 6 3W SMDs instead of 5, or with surface-mount housings.
UPDATE: 12/17/14
I read in a dirty magazine that the '15 F150 will have the option of off-roading LEDs integrated into the side mirrors. What a GOOD idea!