I am working on an old boat, 16ft alum with home made casting decks etc. original merc sized up & have replaced with an old omc 1968 55hp trl-10 is there anything i should be checking before trying to connect the tach. There is a grey wire comming from power pac that i think goes to tach. just not sure if anything different between this omc & merc that was on the boat. just want to make sure i do not hurt the power pack.
