While the CB itself was versatile it was apparent that some units could be smaller and/or specialized for task specific units. "The first departure from the standard CB was the "Special" Construction Battalion, or the "CB Special". "Special" CBs were composed of stevedores and longshoremen who were badly needed for the unloading of cargo in combat zones. Many officers for "Specials" were recruited from the Merchant Marine (and commissioned as CEC) while stevedoring companies were the source of many of the enlisted. Soon, the efficiency of cargo handling in combat zones was on a par to that found in the most efficient ports in the U.S." There were five battalions specialized in pontoons, barges, and causeways: 70th, 81st, 111th, 128th, 302nd. The 134th & 139th CBs were made trucking units due to the transportation and logistic needs on Guam and Okinawa.