[Andy]

I was looking through my parts shelves yesterday and stumbled across this tach that I bought about twenty years ago. I didn’t have a use for it at the time so it’s just been occupying a shelf until now. My question is, does this type of tachometer require a sending unit? It had 4 wires bundled together coming out of the rear of the tach. No idea if they are the original wires…2 were red, 1 black and one yellow. I’d like to use it but I want to be sure I don’t damage it by wiring it up incorrectly. Any advice is appreciated!