higher the mcd = brighter the illumination.
if you are going 'plug and play' with your leds, you'll need six # 194 leds.
You won't get a different color out of it unless you take the cluster apart and wet sand the green color coating off the factory overlay.
Here's a thread that should cover those dept's...
And here's a link that should help you as well....as we used it...Griggs' also has how-to's on doing your switches to led as well...