1940 Ford Pickup recessed tail lights
How to install recessed LED stop/tail/turn lights in a 1940 Ford pickup rear bed panel or similar vehicle. These lights are slightly larger than a 1950 Ford tail light. Could easily be Frenched in to the rear bed pan.
 LED stop/tail/turn lights
There are many different designs of tail lights available to fit all kinds of applications. The type shown below was chosen for a few reasons: one, it was flush mounted with a bezel around the LED light which offered easy and concealed mounting of the light and two, it came ready to use right out of the package.
Surface-mounting was first considered to install the light right on the pan with the four mounting screws that came with it, then simply snapping the bezel over the lens and the job would be done. When the light was taped in the place that it was wanted, and the tail gate installed, the bezel rubbed the tail gate. Moving it downward made the tail light stick out from the contour of the lower pan and it just looked stuck on. Instead, if the lens was recessed into the panel, it would remove an inch of bezel and make a cleaner look to the back of the truck, and no rubbing on the tail gate.
The light that was chosen had a 100,000 hour life, was compatible to most modern signal light systems, and required no additional electrical modifications or doodads, just an easy plug and play installation.
If you're looking for LED lights, this is where this unit was sourced: Oval 6" stop/tail/turn light- surface mount
Begin by removing the chrome bezel from the light assembly and take notice of the nice wide mounting flange that surrounds the red lens cover. The flange has four mounting points; you can use as many as you see fit for your installation.
Take the bezel and a couple of pieces of masking tape. Locate an appropriate place on the pan (in our case) or flat surface of a fender area and tape the bezel to the surface.
Scribe a line around the inside of the bezel.
With a lead pencil or fine marker pen, draw grid lines around the bezel location to act as a guide and measuring point to measure off of.
Measure out the pilot hole centers for both sides of the radius of the light lens. In this case the dimension is 2" so we measure 1 inch from the outside grid lines vertical and horizontal and obtain a center pilot hole for our drill mandrel. Center punch this hole before you drill it.
Drill the pilot holes and set up the punch holes. Here, a 1/2" pilot hole is first made, followed by a 1" punch hole.
Then increase the hole punch size to 2" and take the rest of the excess metal out. Doing it all in one motion may warp the panel, and extra body work may be required.
Make certain that your hole punch is aligned with both horizontal and vertical grid lines before you punch it through. When both holes are done, you then have to remove the metal in between both circles using a thin cut-off wheel, shears or air nibbler.
This is a cut and file-to-fit operation and the end product is in your hands entirely. Fit the light lens to the hole to obtain the best fit possible using a selection of round and flat files, grindstones, and die grinder, working slowly and carefully, trial fitting with your lens often.
It can take a couple of hours to go from rough opening size to final finish to a pair of tail lights. Make sure to spray the edges of the cut opening with a good primer and sealer to avoid any rust problems. To make the tail lights into a faux Frenched look, paint the tail light bezels with body color and glue the bezels to the pan using Marine Goop, if you want that look.
 Lens mounting
There are a couple of ways to mount the lens unit to the pan surface. One choice would be to spot weld a screw stud to the inner surface and mount the light with a star washer to prevent movement, and the other, mount the lens with GE Silicon II caulking. Here a dab was used on each mounting hole (4 of them), then the lens was pressed firmly in place and a piece of masking tape used to hold it in position until the silicon sets up. The light has a 100,000 hour life so shouldn't need replacing any time soon. But if replacement or repair was ever needed, a razor knife will get it out of there fast.