Couple mystery wires?

[Robthetreeman]

I recently purchased a 1995 175hp ocean runner and have a couple most likely simple wiring questions. My tachometer has a separate wire that ran to the previous 1988 175. This motor it looks as if the grey wire runs into the harness. How should I go about wiring my tach? And also the cut wires in the picture I believe the brown is temp but what about the black? I know nothing about wiring so any help is appreciated. Thank you