Apple PowerBook (Duo 270C) - Manual (Page 250)

12. Insert the two pins on the dock bracket into the slot
and hole on the card bracket.
13. Press together the connectors on the card and the slot.
You can push against the plastic part of the connector, as
shown, or against the top of the card. If you push against the
top of the card, make sure the connectors stay properly
aligned.
14. Repeat steps 10–13 to install a second NuBus card, if
you have one; otherwise go to step 15.
Hole
Pin
Slot Pin
234 Chapter 13: Building a PowerBook Duo System