Possible Clues:

• Pop that's over 80 years old
• Radar's quaff, on "M*A*S*H"
• Classic brand of grape soda
• Radar's quaff on "M*A*S*H"
• Radar's soda
• Old soft drink brand
• RC Cola alternative
• Radar's soda brand
• Snapple sister brand
• 'M*A*S*H' soda brand