Transom Support Plate Upper MountTransom Support Plate distributes stress of engine bolts. Cast in high quality aluminum. All plates are 3/8" thick. Fit top bolt pattern of outboard. Generic plate with no lettering is standard, but custom logos and black painting can be produced with minimum quantities. Features:. Distributes stress of engine bolts. High quality cast aluminum. All plates - 3/8" thick. Simple to install