Oops. Sorry for overposting. But, how could Wolfowitz have spoken at SDUSA events from '70-'72, when the org. wasn't founded till early '73 in any real solidified sense?
The split of the SP occurred finally in a formal way at the SP convention in Dec. '72. The right Shactmanites won the convention resolution votes vs. Harrington and whoever remained from the left of Harrington in the McReynolds (who had quit in '71) Debs Caucus. The coalition of the Old (Right) Guard in the SP w/ the Democratic Socialist Federation (which had left the SPA in '36) when they won the vote, in Dec. re-named themselves SDUSA.
See the Gary Dorrien vols. on neo-conservatism.