Mirror Compatibility 3 pin to 5 pin

I recently got a new door from the junk yard and it was to an SL but mine is a base. The SL has 5 pins for the heated mirror option but my mirror only has the 3 pins. Can anyone help me match up which wires go to which or point me to the right section of the service manual. Electric and wires are my most feared things to work on with cars.