Here's an interesting sidebar about LED's.

There is at least one type of LED that changes color based on the electrical input. I think ata +6V to 12V it goes green, between -6V and +6V it shows yellow (or orange) and at -6V to -12V it is red. A neat idea for replacing 'idiot lights!'

I installed Red LED bulbs in my Ford Police Interceptor tail lights but behind the red lenses, they were no more effective than the incandescent bulbs, so I took them out. If I can get some 1157 or 1156 bulbs that put out white light I'd probably try thema gain.

For better tail/stop/turn signals, I'd look into Halogen bulbs over incandescent ones.