I installed LED taillights on both of our 1973 Mustangs. Initially both sets were from Easy Performance, and I needed to run a separate Switched 12 volt wire into the trunk to power the LED panels for the Sequential Flashing feature to work I knew about that special wire in advance). I needed to get power back to the trunk anyway, to power tha wireless backup camera (the "wireless" feature is for the video signal only, the camera and transmitter still need to be powered via a 12 volt switch circuit). The Easy Performance LED panels worked great. Later I came across another vendor offering LED taillight panels, but his design included a microprocessor on each taillight panel, so he did not require a separate 12 volt circuit to be run for Sequential Flashing. Despite the fact our Mach 1 LED Sequential Flashing was working perfectly well, I decided to get yet another LED panel kit from the alternative vendor (VintageLEDs,com) just to see how differently their system was designed.
The VintageLEDs.com panels installed perfectly, as did Easy Performance), and sure enough, I did not need the external power supply. In fairness I need to advise that Easy Performance changed their LED panel design, and they also no longer require the 12 volt switched power to get Sequential Flashing to work. But, the VintageLEDs were also denser, leading to their panels being brighter than the older style Easy Performance LED panels. I never measured how much brighter the VintageLEDs were, as both were far brighter than the oem incandescent light bulbs.
Depending on how much total amperage draws you have on your Turn Signal circuits, you may need to replace the original oem flashers for Turn Signal and 4 way Emergency Flashing to an Electronic Flasher. In fact, I would just bite the bullet and replace them both. The pricing for the new flashers at very inexpensive at the VintageLEDs.com site. I have not checked pricing lately for flashers from Easy Performance.
I have two videos on the LED taillight related work. One shows how to replace the old taillight incandescent bulbs with a new set of LED light panels. That YouTube video is at:
The link showing how to replace the flashers is at:
In short, I am very pleased with both LED sets, but due to the denser LEDs I lean toward VintageLEDs.com. That said, the Easy Performance LED panels on our 73 Mustang Convertible are nice enough and bright enough, that I do not plan to replace them with a set from VintageLEDs.com. I only swapped out the LEDs in the Mach 1 with the VintageLEDs.com units to see how easy they were to install, and to see if I could tell how much brighter they are then the Easy Performance LEDs.