For those that might be interested in the internal workings of the OE rear shock, I cut one apart to have a look. Of course I relieved the pressure and drained the fluid before doing so. Exploded view:
Construction is twin tube, gas pressurized. Rubber bumper on the shaft cushions full extension. Piston has a single disc controlling compression damping and another single disc controlling rebound damping.
The foot valve in the cylinder controls the flow of fluid between the outer tube and the cylinder.
The compression disc is controlled by a star-shaped spring. Under compression fluid passes through the outer slots in the orifice plate. The rebound disc is controlled by a conventional wound spring. Under rebound fluid passes through the inner circular holes.
The orifice plate also has 4 small cutouts that represent a common fluid passage that permits fluid flow in both compression and rebound directions when shaft speed is insufficient to open the discs.
No surprise that this is a very basic shock absorber.