Possible Clues:

• PX patron, perhaps
• Agarn or O'Rourke, in "F Troop": Abbr.
• Second lt.'s subordinate
• Staff sgt., for one
• 1-Across's superior
• Drill sgt., e.g.
• Sergeant or corporal, e.g.
• Sgt. Bilko, e.g.
• ___ Club (military hangout)
• One above a specialist: Abbr.