Here's the details of the one's I build. The schematic is there. http://www.gumpydog.com/bus/MC9_WIP/Electrical/Tail_Light_Converter/tail_light_converter.htmI can't advertise them here, because they're over the $50 limit, but I've sold several of them this year. Pretty easy to build if you have the time to put into it. I use the same relays that are already in the MCI buses so you only have to carry one kind of spare.They're a little more expensive than some of the others that I've seen some use, but they're very reliable.Craig