The challenge: instead of OTL's divide between the working class "Hard Hats" and the bourgeois student hippies, have some solidarity between the two a la Paris in '68, leading not to the Hard Hats attacking the students but rather rioting in support.
Same rough time frame - 1970, but an open post-1900 POD. Only restriction is to keep the war in Vietnam as a focus of the student protests from being completely butterlied (ie other loci are OK).