This info was originally from a Cobra Replica manufacturer who promoted them as a painless swap for 1157 tail light bulbs for better visibility. Like a lot of older cars the Cobra lights have had problems with LEDs and flashers. I’ve managed by hook or crook to get some form of LEDs in the tail lights of my old cars including my GTX, with the exception of my 66 Satellite. Despite a drawer full of various types none worked in the tail lights of the Satellite and I also tried a HD solid state flasher too, which was of no help. So I bought a pair from Amazon and stuck them in this morning and they worked great. They are a red LED so not only are they bright but they are bright red too. One thing noticed is they are substantial in heft - definitely not a cheesy piece of cheap plastic and LED lights stuck in a 1157 base.
Amazon product ASIN B01A77TV4Q
Amazon product ASIN B01A77TV4Q