I forgot about Don't Worry Baby -- I guess what I meant and should have said was: what was his last session as an official member during his first stint (late 1963) before he guested on "Don't Worry Baby" (1964) and then much later TWGMTR sessions (2011-2012). No pressure for an answer, of course; I was just curious.
Tricky question to answer! It depends if he played on the new Little Deuce Coupe album tracks or the single version of Be True to Your School. Since all of the session outtakes and even the final 3-track masters for those are missing, that's a tough call. The LDC album was recorded quickly, over only two or three days, right after Dave quit the band but before the end of his contracted live performances. The tracks all use the same core lineup of piano, one guitar, bass, drums, so it's possible (or even likely, in my opinion) that they were knocked out by the standard '64 studio band of Brian/Carl/Al/Dennis. They sound more like typical Carl guitar and Al bass playing to me. But Dave did at least remember learning some of those songs, so that's potentially unconfirmable until some tapes turn up in an attic.