I have a Yankee 960, 4 wire turn signal unit that I want to install on my 1937 Chrysler (12v, neg ground conversion). Currently, the car has a 7 wire unit installed and it works great...but how do I go to the four wire unit? I have been looking around online and I see references to 'relay units' and the like, but I have not found a nice, step by step wiring diagram for how to do this. As I really am not an ace with electrical projects, I really could use the help. Thanks!