Wiring harness question

There is a part of one of the wiring harnesses that comes off the bulkhead connector and runs back through the fire wall and goes back up under the dash does anyone know what these wires go to.

Need input!!

Color of wires
Type connector on the end
Pictures are good
Do they come off the harness in front of the bulkhead or behind

This part of the harness still has the original harness covering.
There seems to be about 5or 6 wires in the piece of the harness it comes out of the bulkhead connector under the hood and runs back through the firewall through a grommet.

Still need to know a few things here.. Year would help too. Wire colors will help too.

5 or 6 wires right close to the bulkhead connector/fuse block could be the rear light harness if the connector is rectangle shaped and the wires are yellow, lt green, white, tan, brown, blue, black. But usual for that connector is it comes off the fuse block inside the car. Not out and back in.

its a 1971
After the wires go through the firewall they go up toward the head light switch I cant teel you the color of the wires because the car is out at the shop and I am at home.
Its not the reverse light switch and harness I replaced that a while back.

Seems like I remember the 400 turbo downshift switch wiring did that.

IIRC, the 400 detent downshift wire is a single orange wire..There was a tan and orange pair that went to both the detent and the air flapper in 74.

Here's a link to a 71 diagram..

http://www.nrjvette.com/johdotukset/Chevy Corvette 1971.pdf

There is also the heat/AC harness which I believe goes up and over the column to the back of the radio area and then to the console. If I remember correctly, there are about 8 or so different wires going into 3 plugs and then a seperate ground wire.

Isn't there also a small harness that goes to the flasher under the passenger dash?