This LEDs modification to the dome/map/reading lights will result in a output of white light about 2-3 times brighter than the conventional bulbs. I don't recommend using ONLY resisters in series with multiple series of the LEDs. When the engine is running, the voltage could spike up 50V for some moments. Those moments are very short, they have little effect on the slow acting and high power filament bulb. They do, however, have a huge effect on the fragile LEDs. Those spikes could easily triple the current goes throuh the LEDs and burns them out. So, if you use only 1-3 LEDs, in series resistor is acceptable because of the easy of replacement. But in a bulk of 50 LEDs, it is better not to use the resisters only. Here is the circuit diagram:
Parts list (for both sides):
2 - 2"x2.25" predrilled PCBs
2 - LM317T linear voltage regulators (1.5A output current)
72 - T1-3/4 5mm white LEDs (specification provided below)
24 - 62 ohm resisters ( 5% tolerance or better)
2 - 240 ohm resisters ( 5% tolerance or better)
2 - 1.8 Kohm resisters (5% tolerance or better)
2 - 1 uF capacitors
2 - 100 pF capacitors
Soldering iron/gun and solder