IBM RT User's Setup Manual page 212

4. Hold the drive with the printed circuit board on the bottom and
the connectors toward the center of the system unit. Place the
drive on the side rails and slide it into drive position E.
Push the drive in until the plastic latches snap into position,
holding the drive in place.
AJZIF070
Section 2. Removing and Installing Drives in IBM 6150 2-37