Alright, so plenty of people on this site have played with the idea of South Vietnam surviving and whatnot over the years but to my knowlege no one ever aims for a different non-communist, Indochina nation's survival, so here goes:
With a POD no earlier then the 18 March 1970 overthrow of the Cambodian monarchy, have the Khmer Republic survive without the survival of Non-Communist governments in Laos and South Vietnam.