Two plugs in harness behind inst. cluster?

I have an 88 TC with 5spd.. It has every option that I believe they came with except for the moonroof. I took the cluster out the other day to rewire for the stereo and when I removed the cluster I noticed that there were two plugs behind there. One is the larger plug which plugs into the cluster. The other plug was not connected to anything. It is not affecting anything that I can tell but I would like to know what it went/goes to. Was this an option of some sort as in an electronic cluster? I have searched for this both here and on the other popular forums regarding our types of cars with no results of any kind. Any info would be most appreciated. Thanks in advance. Oh and by the way this forum is awesome. I have learned much from reading the endless subjects here. This is my first TC but I don't ever plan on seeing her go anywhere. The car is in great shape and only needs a little tlc due to minor neglect on the previous owners part. No rust.

Does your PRC light work? What about ABS light. Both of these are powered by their own plugs, not through the cluster plug.

-Shane

Aha. That would answer that question. He did tell me that he changed the cluster to the older style for the higher reading turbo guage. That would explain the extra plug behind the cluster. Thanks alot man. I appreciate your taking the time to answer such a simple question.