mercruiser alternator question

[IAMHOOKINGUP]

I have a 1990 4.3l mercruiser I/O. Ther alternator recently died. I had it rebuilt. There are three wires that connect to it a thick positive red wire, and two others. The other two are an excitor and a sensor. The problem i that the exictor and sensor wires are the same color coming off the motor"whoever had the boat before me must have changed them" Is there a test that I can do to tell which wire is which?<br /><br />Thanks\<br />Al