1964 strength was one brigade of four battalions; the Marines were part of the Navy until 5 Jan 1965 when made a separate service. A fifth battalion was active by Mar 1965 (two in II CTZ and three in III CTZ); in Nov 1965 sixth battalion was authorized. 1967 strength was six infantry battalions and three artillery batteries (the batteries had been equipped with 75mm pack howitzers, slowly converting to 105mm howitzers; the last one was authorized for conversion late Oct 1966). The artillery grew to five or six batteries. The Marine Division was activated 1 Oct 1968, although not completed until later. By Jun 1969 there were two artillery battalions (the 1st formed 1 Apr 1969 and the 2nd soon after); infantry strength was still at six battalions. The 3rd Artillery Bn was activated Nov 1969 and the 7th Infantry Bn Dec 1969. There were nine battalions by the end of 1970.
The division, by this time, had two task force headquarters (A and B), which soon became known as brigade headquarters. When they grew to nine battalions, there was also a Brigade C. In Jun 1971 these were numbered, initially based on the battalions assigned (e.g., Brigade A had the 1st, 4th and 7th Bns and became 147th Bde; B had the 2nd, 5th and 6th and became 256th.) However, these numbers were changed and the finalization ca Nov 1971 was 147th, 258th and 369th [147th Bde may have had 1st, 4th, 8th Bns]. The division also included three small reconnaissance companies (one for each brigade) and an engineer battalion.
In 1974, the Marine Division was supplemented by raising the 468th Marine Brigade. It was operational by Jan 1975.