It was different then. :shrug:
LBJ decided AGAINST activating Guard and Reserve units. Some of those guardsmen/reservists who were activated actually filed suit. Less than 20,000 Reserve and Guard soldiers were called up in 1968 and
approximately 12,500 deployed to Vietnam.
The Vietnam War delayed implementation of the new policy. It also distorted Army Reserve and National Guard development by flooding both with recruits eager to avoid the draft and possible duty in Vietnam. President Lyndon B. Johnson, despite the advice of the Joint Chiefs of Staff, refused to mobilize reserve components. Johnson relented with a limited call‐up in 1968. Forty‐two Army Reserve units answered the call (nearly 8,000 men), 32 of which went to Vietnam. Nearly all the units were detachments or companies providing support services.
http://www.answers.com/topic/army-reserves-and-national-guardNo massive call-ups of National Guard troops occurred to meet the country's military manpower requirements during the Vietnam War. Mobilization of large numbers of Guardsmen would have been inconsistent with President Lyndon B. Johnson's attempt to portray the war as a limited conflict that could be fought with resources already available to the regular Army. Johnson chose to rely on an increased draft and a one-year tour of duty rotation policy to fight the Vietnam War instead of activating significant numbers of National Guardsmen.
The popular perception that National Guardsmen were not used in Vietnam, however, is incorrect. On May 13, 1968, in response to the Lunar New Year (Tet) communist attacks on South Vietnam, President Johnson activated 20 Army National Guard combat units and 12 combat support and combat service support units. Of the 12,234 mobilized, 2,729 reported to Vietnam with their units. Of the 9,505 initially remaining in the United States, 4,311 subsequently were assigned to Vietnam, bringing the total number of mobilized Army Guard members in the Republic of Vietnam to 7,040. All Army Guard units were released from active duty by December 12, 1969. Included among the more than 4,000 awards earned by Army Guard members in Vietnam were 55 Silver Stars, 681 Purple Hearts, one Distinguished Flying Cross, 16 Distinguished Service Medals, six Legions of Merit, and over 1,000 Bronze Stars.
Company D (Ranger) of the 151st Infantry, Indiana Army National Guard arrived in country in December of 1968. The Indiana Rangers were assigned reconnaissance and intelligence-gathering missions. Operating deep in enemy territory, Ranger patrols engaged enemy units while conducting raids, ambushes and surveillance missions. "Delta Company" achieved an impressive combat record; unit members earned 510 medals for valor and service.
Many National Guard units not mobilized for the Vietnam War saw action of a different sort during the 1960s. Beginning with Newark, New Jersey in 1964, racially motivated riots broke out in many large American cities. Units of the National Guard were called out to stop burning and looting in Los Angeles, Washington, D.C., Detroit, and a host of other cities. As the anti-war movement gathered momentum in the late 1960s, Guardsmen were called out to maintain order during large demonstrations.
Secretary of Defense Melvin Laird explained the new "Total Force Concept" in a press conference on 21 August 1970. Laird explained that the president's requested reductions of defense expenditures would require reductions in all facets of the active forces and increased reliance on the combat and combat support units of the National Guard and the Reserves. He further stated that "a total force concept (would) be applied in all aspects of planning, programming, manning, equipping, and employing Guard and Reserve forces. The Total Force Concept brought a new level of support for the National Guard and Reserves. General Creighton Abrams, United States Army Chief of Staff, reorganized the "Total Army" so that the Regular Army could not conduct an extended campaign without mobilizing the Guard and Reserves, thus gaining the involvement and, hopefully, the support of small-town America.
http://www.globalsecurity.org/military/agency/army/arng-history.htm