Possible Clues:

• Deejay Casey
• DJ Casey
• Casey of 'American Top 40'
• Top 40 DJ Casey
• Casey of Top 40 fame
• Shaggy's voice
• Casey who provided Shaggy's voice in TV's "Scooby-Doo"
• "Casey's Top 40" host
• Casey of radio countdowns
• Longtime "American Top 40" host