If you are referring to the structural support riveted to the back from lower, left corner to right corner, that is builder made from stock 3/4" angle. Can't remember if it was 1/16 or 1/8.
Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
|