Classic Mac Find

I picked up a couple of macs at a Goodwill store a couple of days ago and found a connector with them that im not sure what it is and wanted to see if anyone on here might know what it is. The items I picked up were Performa 637cd Quadra 660av 15" Multiscan Monitor Modem 2 Keyboards 1 mouse and this connector has the following config at the open end it has 5 rows of very small female connectors at the other end it has 4 wires, one is a video connector, one is a keyboard/mouse and a speaker and mic connector. Can anyone tell me what this is? Also I was able to get this all for 25$ The 637cd works great but haven't been able to test the 660av since I need a special connector to get it to work with this monitor. Also if anyone has a connector to hook this monitor up to the 660av please let me know. Thanks Jim