Turn is straight forward - find the wire, tap in a resistor (10Ω worked for me.) Tail is different because it's actually two positive lines, each with it's own power expectations. For stop I used a 12Ω and for running I used a 50Ω. In total you will need 3 resistors that are roughly calculated to match the power draw of each bulb when combined with your new LEDs. 25w minimum rating, but 50w would be safer. Resistance requirements will vary based on which bulbs you get but this is a good start. My 500 was particularly picky to not go to low OR high or it would shut down the circuit and give a bulb out error. Avoid the 50w 6Ω places try to sell you - they are really only meant for high output bulbs! They end up pulling too much power on lines that are targeting 21w.