Possible Clues:

• Soft drink that sounds like a bit of footwear
• Moxie rival
• Vintage soda
• Dr Pepper sister brand
• Throwback pop?
• ___ Bottling Company (Cleveland fixture for over 85 years)
• Radar's quaff, on 'M*A*S*H'
• Soda brand introduced in 1924
• Soda served at Rosie's Bar on 'M*A*S*H'
• Radar O'Reilly's pop brand