I replaced the tail lights, back up lights, and front parking/turn signal lights with LEDs in my 73 Cuda. My primary reason was to reduce the heat under the plastic lenses, because I found that some of the plastic sockets had deformed a bit due to the heat produced by the 1157 incandescent bulbs.
Here are the part numbers that I used:
1) Tail lights - Sylvania Zevo 1157R (red LED)
2) Back up lights - Sylvania 1156 (clear LED)
3) Front parking/turn signal lights - Sylvania Zevo 1157A (amber LED)
4) Turn signal flasher - United Pacific 90652
What I like about these LEDs is that they are a direct replacement for 1157 bulbs and they are really bright! Do a search and you'll find some YouTube videos about them.
The main drawback is the cost. A pack of 2 LEDs costs around $20-$25 and the flasher costs around $15, so it's definitely more expensive than traditional incandescent bulbs.
Hope this helps.