The 121st CB was decommissioned in December and re-designated CBD 1504. In January 1947 CBs 104 and 105 were reactivated. The 30th NCR was home-ported on Guam composed of CBDs 1501-13 and NCB 103. In 1949, the 103rd was made a Mobile Construction Battalion (MCB) while CBs 104 and 105 were made Amphibious Construction Battalions(ACBs). From 1949 until 1968 CBs were designated MCBs. In 1949 MCB 1 was reactivated at Naval Amphibious Base Little Creek, VA. In June 1950 the NCF totaled a few thousand.