Check out this website. Leds are pre wired and they even have the matching power supply and a nice adapter for wiring.
I bought 3 of the 3 leds but ended up using only 2. http://autolumination.com/fixtures.htm
you have to scroll down page to see leds.
I figured out what I did wrong. The cristmas lights have a cone dimple in the top to disperse light and none of it passes straight out. I cliped off the dimple, sanded, then polished the LEDs. Perfect.