According to the wiki: Piper Laurie (Catherine), Lara Flynn Boyle (Donna Hayward) [good riddance], Michael J. Anderson (The Man from Another Place), Joan Chen (Josie Packard), Michael Ontkean (Sheriff Harry S. Truman) [ :( ], Eric Da Ra (Leo Johnson), and Heather Graham (Annie Blackburn).
I'm bummed about Michael Ontkean not returning. He's retired IIRC
Boyle was always a bit of wrench off-screen, she lobbied against a lot of the more risque stuff that was proposed plot wise
Yeah - Boyle was the one that vetoed the Cooper-Audrey relationship because her and McLaughlin were in a relationship at the time in reality.
Definitely gonna be missing a little something without Ontkean, I felt he brought that nice down-to-earth folksy vibe to provide contrast to Cooper's eccentric approach to things.