72 Torino/Ranchero GT guage cluster

I want to replace the stock cluster with the performance one.  My guage cluster has a large black plug that the stock one doesn't have.  As best I can tell it feeds the clock and tach.  I thought the car would be wired for the interchange but can find no connector in the dash for this large black plug.  Anyone out there have any experience with these things?
 
Thanks,  John

First - you'll have even more trouble if your vehicle didn't have the stock tachometer or clock. You'll have to have an idea of the specific wires in the harness that feed the tach and clock and simply seperate them into the new plug making sure to add any grounds where necessary.