In 1968 the Marine Corps requested that the Navy make a change. The Marines were using "MCB" for Marine Corps Base while the Navy was using "MCB" for Mobile Construction Battalion, it was causing confusion in logistics. The Navy agreed and added "Naval" to MCB creating the NMCBs that now exist. During that year the 30th NCR had five battalions in the Da Nang area and two at Chu Lai. The 32nd NCR had three battalions tasked near Phu Bai and one at Dong Ha. In May 1968 two reserve battalions RNMCB 12 and 22 were activated, bring the total number of battalions in Vietnam to 21. Both ACBs were in theater as well as CBMUs 301 and 302. In 1968 NMCB 10 drew an atypical Seabee "task" supporting the 101st Airborne. During 1969 the number of Seabees deployed reached 29,000, from there their draw-down began. The last battalion withdrew late 1971 with the last Seabee teams out a year later. When it was over they had sent 137 Seabee teams, built 15 CB camps, and deployed 22 battalions. CBMU 302 became the largest CB ever at over 1400 men and was homeported at Cam Rahn Bay. On 23 April 1975 it was announced that U.S. involvement in Vietnam was over.