Ran into a newer Wiring Harness-questions

[72step]

My uncle had bought a wrecked 67-72 Chevy pickup last year (not sure what year) for parts and only had a banged up cab left over after he parted it out and used the parts he needed for his project 68 and pretty much sold the rest. Long story short he told me to come over and see if there was anything left on it before he sends it to the recyclers. He said I could have anything I need. I went over and it was pretty much plucked clean and was pretty beat to begin with. I was already going to go home when I started to look at the wires and it has a newer wiring harness with the small push in newer fuses and the wires are all labeled on the wire all the way what they are. I'm going back to get it in the morning cuz it was almost dark but man that's just what I needed. They cut parts of it behind the cab but even if I have to add on no prob here! It wasn't really installed too proffesional just zip tied- it was just an old rusty firewood gettin work truck. My truck really needs a new harness. How do I know what brand it is? It would help to know so I can download some directions and see if it's worth trying to install.

P.S. How's a easy way to take off the back glass?--That's the only other thing worth taking.