When it comes to cool new stuff for vintage Mustangs, owners of '71-'73s are usually the last to get it, if at all. But it hasn't taken long for Mustang Project, a company known for its LED sequential taillights for vintage Mustangs, to break into the big-Mustang market. With Mustang Project's new kit, sequential taillight operation, originally made popular with the '67-'70 Shelbys, is now available for the last of the first-generation Mustangs. As a bonus, the LED lights are much brighter than bulbs, which add to safety by improving the car's visibility to other motorists.
Although the '71-'73 taillights feature the Mustang's recognizable three-lens taillights, only two of the lens panels are used for taillights and brake lights. The center lens is for the back-up light. For that reason, the sequential operation for '71-'73s is a two-blinker affair, not three as on previous Mustangs. That means the inner taillight flashes before the outer light.
While installation is simple, as we learned at Classic Creations of Central Florida, it's a bit more complicated than earlier models because the taillight housings must be removed from the car so the lens can be separated from the main housing. The Mustang Project LEDs replace the original bulbs, but because the rectangular LED panels won't fit through the original bulb-socket openings at the rear of the housings, the LEDs must go in from the front after removing the lens.
To slow down the rate of flash, providing time for the sequential operation, the kit also includes a new flasher unit, which replaces the round factory flasher behind the glove compartment.
 Mustang Project's LED sequential-taillight...  Mustang Project's LED sequential-taillight kit for '71-'73 Mustangs is fairly basic. It comes with four LED panels (two inner and two outer) and a replacement flasher unit that slows down the turn-signal flasher to provide time for the sequential action. |  To install the LED taillights,...  To install the LED taillights, the '71-'73 taillight housing must be removed from inside the trunk. Pop out the light-bulb sockets (two for the taillights and a center one for the back-up light), and remove the four nuts that secure the housing to the rear panel. |  Because the LED panels are...  Because the LED panels are too large for the housing's small bulb openings, the taillight lens must be removed from the housing. The lens attaches to the housing with three tabs, one at the top and two at the bottom. Use a flat-blade screwdriver or similar tool to carefully pry the top tab out of its slot to separate the two pieces. |
 Once the top tab is popped...  Once the top tab is popped out, the lens can be separated from the housing. Someone had used adhesive to secure the lens gasket to our housing, so it took a bit more careful prying to pull the two plastic pieces apart. |  To prepare for the LED panels,...  To prepare for the LED panels, remove the taillight bulbs from the sockets. The center bulb is the back-up light, so it is retained. |  With the housing inside the...  With the housing inside the trunk, reinstall the bulb sockets, then install the LED panels from the inside. Be sure the LEDs are used in the correct positions, inner and outer. Mustang Project supplies them in bags marked accordingly. |
 A small Phillips screw in...  A small Phillips screw in the LED panel allows adjustment to make sure the panel is positioned vertically in the housing. |  Mustang Project's flasher...  Mustang Project's flasher unit replaces the factory flasher, a canister-style unit that is located above the glovebox on '71-'73 Mustangs. Switch on the turn signals to locate it by sound. The Mustang Project flasher includes a ground wire, which can be connected to one of the glovebox screws. |  It's a good idea to test the...  It's a good idea to test the LEDs before putting the lens and housing back together. If everything works, reinstall the housings and enjoy your sequential taillights. |