Dave:
Some history: Clark Equipment Company sold the Industrial Truck Division (ITD) to Terex in 1992. Around the same time, Clark Equipment discontinued their pension plan. Old timers (like myself), who had been vested for many years, would still get their 1/2 pension when they turned 55 or full pension when they reached 65. Younger employees were cashed out. This was in the U.S.; the pension plan might have been different at other Clark plants. In 1995, Ingersoll-Rand (I-R) acquired Clark Equipment in a hostile takeover. I-R kept what they wanted (Bobcat, Club Car and Blaw-Knox) and sold what they did not (Axles and Transmissions went to Dana). Meanwhile, Clark Material Handling (CMHC)(the former ITD of Clark Equipment) took itself private and got away from its unhappy marriage with Terex. In 1998, during the IMF meltdown, CMHC acquired Samsung Lift Truck, its former joint-venture partner in Korea. In 2000, CMHC was forced to declare bankruptcy and in 2003 was acquired by the Young An Hat Company of Korea.
Regarding Clark Equipement's pension plan, it was administered by I-R from 1995 to 2007. In 2007, I-R sold the Bobcat business to Doosan Infracore and included the Clark pension plan responsibility with the deal. In 2008, my monthly checks from the Clark pension plan changed from I-R to Doosan.
Short take: You will need to contact Doosan in the U.S. to get the necessary information to determine your eligibility.
Good luck.
Joe