Soldier of Fortune by Barry Sadler (Casca Series, Book 8) by Books In Motion.com

The Cambodian Jungle is an easy place to die for most men, but not Casca Longinus. Cursed to live and fight as a soldier through millenia, the eternal mercenary finds himself deep in the misty heart of a jungle war. Endless miles of vermin-infested swamp become his stalking ground, while he in turn is hunted constantly by the Khmer Rouge. The stakes are high, but it is also a chance for Casca (Casey Romaine) to earn $200,000. It is a price he considers fair for what would be a suicide mission to any other man. To earn it he must parachute into a tropical hell, rescue a family of Chinese refugees, and bring them back to Taiwan...alive!