installing cab corner moulding?

[C&C Chevy]

My cab corner moulding (6) has disappeard! I can only assume that it flew off going down the road...

Anyway, going to get another one, but not from LMC! They want 119$ for just one! I have a buddy that has a few part trucks and see if he has any laying around. I was going to get another mounting bracket (8) from LMC cause its only $5 and I think mine is broke (thus it flyin off!).

Finally, here's the question. How do you get the corner piece on? I looked at the bracket and don't understand how it goes on. I know it slides into the mouling on the back of the cab, but how does the mounting bracket work? Thanks.