Johnsons & guests to San Fernando Church in San Antonio for Latin American Ambassadors service; none of the Ambassadors attended; sermon on Vietnam; Johnsons to Balcones Research Center for meeting about LBJ Library stone; helicopter to Camp Mabry; hamburgers at Don Thomas' home in Austin; Johnsons tour possible house for Luci & Pat Nugent; to ranch to discuss remodeling plans; Johnsons & guests drive around ranches; dinner; back to White House with Luci Nugent