Unit installed in 1973, (matched to an 85HP Evinrude) but the boat doesn't have a Tach. So I bought one (used OMC from around the same era) that the guy said 'it should plug right in', and I believe him.... but where?<br /><br />I assume that because all the wires go to the Control box from the motor, he was meaning it should plug in there, but I can't see where it would, outwardly.<br /><br />Do I hafta take apart the Control Box to plug it in? Besides the Power lead and the Ground there's a small square connector.<br /><br />Anybody have any experience doing this? I have a wiring diagram for the motor, but I'm not gonna run a wire all the way back there if I don't hafta.....