P1 is a High-Speed Terminal Strip with Rugged Ground Plan manufactured by Samtec (http://www.samtec.com/). It has a middle bar that is used for ground and power connections. The part number for P1 is QFS-104-06.25-SL-D-A. The figure below shows a schematic diagram of P1.
GX3700 Expansion Board – Host Connectors
J1 and J2 are used to connect the expansion board signals to the user application. Each one is a dual VHDCI 68 pins. There are few vendors for these connectors; one option is Honda PN HDRA-E68W1LFDTC-SL+. Each connector has two parts A and B. J1A corresponds to J2 on the front panel, J1B to J1, J2A to J4 and J2B to J3 on the front panel. Customers can us other connectors for their application but that will require changing the design of the front panel.