87 4.3 lx with 55 amp alt. 0 output voltage at post on alt. when i got boat excite wire (orange) was disconnected at alt.i jumped 12 volts from battery to alt output post to excite alt. still no ouput.cant i put a single wire alt. on (marine alt). if so what do i do with purple and red/purple wires for the original mando alt. also my tach doesnt work. appreciate the help.
