Commonly referred to as "Bouncy seats," are front seats that travel vertically and are hydraulically dampened. Mine have a large circular adjustment for firm or soft, a latch to lock the seat down, and a small shock absorber. However, this appears to be quite different from what you describe, to what many refer to "Bouncy seats." Good luck.
92 Montero LS, Rancho Shocks, Hellas, AirLift bags,
99 Superduty 7.3, Rancho 9000s, Superchip, Banks Billet Torque Converter, AirRaid, BFG's, Pillar Guages, 4.5" Exhaust