How hard to add rear cab trim?

[rs74]

My 85 c10 doesn't have the rear cab trim and I would like to ad it. Does the long piece have clips that hood onto rivets or something like that on the back of cab.
How are the clips attached is what I am wondering about. How hard would it be to add this to my truck. If I am not mistaken the corner pieces attach with screws coming from the inside of the cab through to the trim pieces. I like the look just don't know how hard it would be to put on. Not sure if it originally came with it not.