It should be ready to go. Remove the black and gray wires outside the lumineire and connect a section (lets' say, 6') of 16/3 or 14/3 sjo cord with a 15 amp plug. Connect the cord's white wire to the (2) ballasts com. (common, grey or white colored) wires. Connect the green to the metal luminiere enclosure. Connect the black cord wire to the (2) ballasts 120 hot wires (probably black)A wire may be from the ballast for 277 volt (could be an orange colored) wire. This may be cut off and covered with electrical tap, or it may have had a terminal strip to connect a wire to. Anyway, you do not wire anything to this.

Shov