You have to first somehow make sure that the French did'nt attempt to do their best to Screw Vietnam over during independence by attempting to get it partitioned. Secondly, if the USA treated Ho Chi Minh as more of a Nationalist than a Communist( And Ho was infinitely more pragmatic then the likes of Mao, not to mention the fact that he was more nationalistic than communist in many many ways) , and exploited the traditonal Vietnamnese distrust of the Chinese, then the Vietnam War Get's entirely butteflied away, and Vietnam forms part of the Southern perimeter of the Containment strategy against China.
Oh , and the same generous trade terms the Koreans were given.