The 1956 design of the Marine Corps Utility Shirt was identical to the P53 model, but was made from cotton sateen rather than herringbone twill (HBT).1 The P56 was replaced with the Army's OG-107 utility shirt in 1964 and was rarely worn in Vietnam.1. Cataloging And Identification Guide For 20th Century Uniforms (Marine Corps Museum, 1987)