Brand new - not rebuilt
SPLINED CLUCH SHAFT COUPLER
#1 The splined area sticks out further on one side of the disc than the other. The side that sticks out further goes to the back of the tractor. The flatter side goes to the flywheel.
#2 The clutch design has changed several times over the years. Some may use springs and some may use rubber dampers. They all work exactly the same. Yours may LOOK a little different though.