I have done a lot of research on this for my first gen on putting LED bulbs in my tail lights since they do not make after market LED tails.
99% of what I found said that you need to solder a load resistor in line with the bulb to slow down the flashing of the bulb, because if you just put the LED bulb in and go, it will blink like its having a seizure.
So, Searched for about an hour for DIY LED tail lights and found this solution, since I heard the load resistors can get quite hot.
All you need to do is get one of these LED flashers
LED Flashers Blinkers Resistors Load Equalizers for Turn Signal Replacement Bulbs Rapid Flashing Fix
You can mix LED's and incadesant and the flash rate will be right.
Now on the first gen, you would use the EFL-2, for second GEN I am not sure which one you would use. might be the same.
I thought I would pass this info along for anyone wanting/considering to convert to LED for tails/blinkers/parking lights.