wiring harness going behind the motor

[Boggin]

hey guys, on my project truck im took the wiring harness out since im doing the cab swap so ill be using the other wiring harness. and the harness would go back behind the engine, a couple wires going to the TFI and then like 5 or 6 going back up under the truck under the firewall somewhere. i was just wondering what these are for, since i could not find any connections for them i figured oh well cut em off so i did so. i guess when i have the cab off, i can take the wires from wherever they go from the donor truck and put on this one. so i was just wondering what those wires were for? the truck is automatic so i figured they might be for that but i am swapping in a 5spd so i wont need them if thats what theyre for. so i was just wondering what theyre for like tail lights or fuel pump or guages?
thanks alot

 

[adsm08]

Lights, gauges, and pumps run along the driver's side back there in the corner.

Pics would be helpful but I'm sure at least some of that was for the auto trans.