Bendix King KMA24 Marker Beacon Audio Panel - P/N 066-1055-03.  Recently removed in full working order from a Mooney M20K.  

Comes with the mounting tray.  

• Compact, fully solid-state unit containing pushbutton audio selector panel, speaker and headphone isolation amplifiers, and a marker beacon receiver
• Styled to match with the other King Silver Crown units but can be integrated into any 500 ohm output audio system
• Can handle as many three transceivers and six receivers
• Models with different features and combinations of marker light presentation, AUTO, 2 COMMs, 2 NAVs, DME, ADF, HF, TEL selections (see table below)
• Has two unswitched inputs for use as altimeter warning and telephone ringer
• Has outputs for ramp hailer and passenger address or intercom
• Seperate isolation amplifiers are provided for headphones and speaker to provide isolation even when the same source is selected
• Automatic dimmimg for marker beacon lights
• 14V or 28VDC operation
• TSO'd