Random alternator installation question
 

I am putting a new alternator into my Volvo 740GLE. The old alternator has 3 electrical connections on the back, but the new one only seems to have 2 - unless you remove a plug that's connected to something that looks like a little black box (capacitor?) on the back of the alternator; the 3rd plug fits perfectly onto that plug.

Is this what you're supposed to do?