I cut .063 X 3/4" X 3/4" angle for the left and right stack brackets. I will mount all the trays to the angle with #6 screws. The angles will be riveted to the panel with 7 (Each side) -3 flush rivets.I placed each tray in between the angles then placed the radio in the tray. I wanted these radios to line up all the way to the top. Once I got the Trasponder done on the bottom I moved on to the SL40. The Garmin 327 transponder tray isn't flush with the front of the panel but the rest of the racks are. SL40, SL30, KMD 150 and PS 6000,
