The standard SPI interface for SBC-3 is a 10-pin header. It has dual Gnd, +5v, and +9v power; and SCK, MISO, MOSI, and SS SPI signals.
All of the devices listed under this section use these SPI ports. The SBC-3 SPI ports have Slave Select (SS) pins numbered 0 thru 5, and 7. SS6 is used by the onboard ATMega8.
Here's the pin layout: