Help with bumper identification

[rainamy]

Can someone help me figure out what I've got here?

As far as ive ever known and always understood, 73-80 bumpers didn't wrap over around the fenders, and 81-up did.

Also, I understood you could put an 81-up bumper on an earlier frame, but, there would be issues with mounting at the frame horn you would need to address.

My parts truck has a bumper that wraps around to the fenders, but doesn't interfere with them. But it also meet up flush with the frame horns and mounts.

So what is it, and in selling it, what is it supposed to be for? I had people interested who thought it was 73-80 but I thought it was 81-up...