well the big grey plug, that one will hook up to the other part of your engine wiring harness. The one other grey plug by itself is the 02 sensor plug, the plugs you shouldnt worry about at all, its all self explanitory once everything is in..... it just plugs right up..... the rest of the 5 wires you just have to splice in and you can color match them to your exiasting old chassis harness.
oh and hte white plug all by itself is the e-plug, that one will hook up to the ecu...