can anyone tell me what kind and how to install an ignition kill switch on a 1978 mercury 20 hp eletric start. ive looked at a few but nothing applys to my motor and instructions say to ask marine sales and service most of us doityourselfers get i dont know from sales or service only wants to charge to do it for you. the ones ive looked at some have 4 prongs some have 2 wires witch are alot smaller than 14 gauge ignition wires thanks anything would help