Hey, that looks exactly like my '88, wire colors and all.
I found that that half of the wires are for the driving lights, 3 are for the internal lights and power, and 2 are power and ground. I actually tossed the whole thing and got a 7-way junction box, and butt spliced the 3 inside lighting wires. But it was complicated to put together.
What colors do you need? I can tell you that Brown is Right Turn, Red is Left Turn, Yellow is backup, and Green is Marker/ Tail Lights. Howeeeeeever, there is a second Yellow wire, and it's one of the Internal Lights.