Years ago someone directed me to this company that made a little black box unit that would make the tailights flash on and off. It worked great but I cant remember if it was set up for Positive ground or not? I've since switched to negative ground and I'd like to talk to the person or company I bought the unit from to see how to hook it up using Negative ground. A google search brings up a CK Technologies but it's not the company I'm looking for. Anyone know the unit I'm talking about. Thanks in advance. Karl