L e d s tail lights on my 64
Just go to the local AutoZone / Kragen /O-really? / type chain store, and buy an LF12 Tridon flasher.
Two terminals, direct replacement. It will flash any combination of regular bulbs & LED's. It will flash 20 regular bulbs. Or one.
Only down side is you need to check your lamps on a regular basis. It will still flash with a dead bulb, so if you have a front out you will never know it. On the up side, the rear will still flash with a dead front...
B.