Jack Truman was an agent of the international espionage outfit S.H.I.E.L.D. who was badly injured during a mission to capture Cable and subsequently transformed into a cyborg to battle the Red Skull. He later swapped his minds into the body of another former S.H.I.E.L.D. agent, Larry Young. Truman is presumably living a normal human life in Young's body, while Young is presumably still trapped in the Deathlok body.
Truman reappeared later, and played a role in shepherding the Teen Brigade against the Young Masters. He assisted them in their battle against the Masters in the capital of Latveria, where the Young Masters intended to assassinate Kristoff Vernard.