66 dart LED prototype working for now

The two (and only two) LED bulbs worth trying in place of an 1157 in a brake/tail light are these and these (this second link is the only type that has a chance of working in lamps that have fresnel lenses, that's the type with the round "bullseye" in the middle with a series of rings around it).

Front turn signals with fresnel lenses: outta luck; there's no legitimate amber or white LED bulb that will work with them. With the other kind—a reflector bowl behind the bulb and rectangular/square little pillow-shaped optics in the lens, the one to try is this one.

That "trying" language is on purpose; unlike with spec (filament) bulbs, physical fit doesn't guarantee adequate optical match-up between the bulb and the lamp, so you need to assess the performance of these bulbs in your particular lamps by comparing them side-by-side with the original incandescents as reasonably well described here.

Back-up lights are easy, that's always this one.

Don't forget, LEDs in the front and/or rear turn signals will necessitate a different turn signal flasher; that's this one (2-prong like original; connect its ground wire conveniently).

Sh'boom!