The 77317-803-40: The post finish is tin at 78.7 µinch (2.00 µm), standard for solder-joint reliability in through-hole wave-solder processes.
In a board-stack application, the mated receptacle adds its own height; budget at least 0.400" total above the board for the mated pair. The square pin contact (phosphor bronze) mates with standard BERGSTIK receptacles and many third-party 0.025"-square pin sockets. No shrouding means the pins are exposed — handle with care during assembly to avoid bending.