This Drive-In Speaker has a secret mystery cryptic message written INSIDE! What does it say?

This drive-in speaker had everything going against it - someone marked "Does Not Work" on the back, it was filled with sand and dirt, and there was even a cryptic message about where this unit's original home. But I'm going to fix it once again! But I'm going to restore this bad boy and make it work once more. Follow along with me! My drive-in speakers and other restorations are available at http://chuckmillercreatives.etsy.com