Is there a sub harness for power windows, what I'm talking about is behind the dash inside the car the main chassis harness.

Or is it simply that the chassis harness for cars with power windows is different?

 

They are different. I have a '90 that came with manual windows. I had to run wires under the dash to install the power windows.

 

my 87 has like every wire for every option in it i think, the doors and everything are wired up for pw windows, mirrors locks, i found this out putting in the pwr locks, the passenger side door was plugged in behind the kick panel, same with drivers side, once i pulled the kick panel i could see where the wires were leading from the door, pretty sure it goes back to fuse panel