Vietnam War without Sino-Soviet split

As the tin says. What difference would it have made if the Chinese and Soviet had still been allies during the Vietnam War?
Also interested in effects on the American political landscape.
 
The only difference it would have made would have been after the Tet Offensive, as that would have strengthened immeasurably the hand of North Vietnam, arguably butterflying away the post-1975 wars in Indochina as they happened IOTL by either ensuring they don't happen at all or both the USSR and PRC agree on suppressing the Khmer Rouge before they get fairly started.
 
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