I need some help on what I need for the RPM lead/sensor for my mychron 3. I bought a used mychron that came with a black wire I was told is for the RPM but it doesn’t have any type of connector on either end? I assume it’s suppose to plug into the back of the gauge (like the temp sensor) and then wrap around the plug wire? Do I need to buy a patch cable or what? When I look up pics of a new RPM lead it doesn’t show any type of connector on either end either? Am I missing something?