When your 1947-1955 GM truck needs rear cab corners and you prefer original US made replacement parts, there is an alternative.
Surprise: These lower corners have the same round shape as the upper corners. Locate a cab that is considered a total loss and cut out the upper rear corners. They can be trimmed to replace the area of need on your rusted bottom edges. The metal gauge and curvature will be correct. For best results use the upper right corner on the lower left and the upper left on the lower right.
This tip comes from Richard Pasauage of Wilkes-Barre, PA. He personally made this repair on his 1950 Chevrolet truck and is very happy with the results.