mac monster 5" tacho v msd streetfire

hello, have jusr picked up a monster 5" mac tacho for my cuda that is currently running a week old msd streetfire that i dont want to fk up :D the wires on the tacho are red black,white green guessting red perm +12v, black -12v white ign or lights on and green to msd tach output? any thoughts well appreciated, car going into paint shop next week, om real exited!