Just installed the mailbox on the lot of the “almost ours” house.
Assembly and installation were quite simple. I used a 4x4 as well as a bag of Quikcrete for extra support.
No issues with holes lining up, all connections were fine.  The latch to the mailbox door was a bit loose, but a simple adjustment seems to have fixed the problem.  
I thought the mailbox would have been made of thicker metal, but I’ll have to wait and see if that is an issue.
All things considered, I am happy with the mailbox.