The earlier SC-1 S/C-Knob (left side) has a square shutter release button and is matching the MD-1 motor drive.
Type 1 has straight-slotted screws and it doesn't have the lift-to-turn mechanism.
Examples:Type 2 has straight-slotted screws and the same lift-to-turn mechanism as the SC-2 S/C Knob.
Examples:Type 3 has JIS cross drive headed screws and the same lift-to-turn mechanism as the SC-2 S/C Knob.
Examples:
The later SC-2 S/C-Knob (right side) has a round shutter release button and is matching the MD-2 motor drive. It has JIS cross drive headed screws and the lift-to-turn mechanism.
Examples: