Thanks to Dan Hughes for this tip!
Formed in 1963 The Evergreen Blues Band (Rick Barrio, Tom Bray, Manny Esparza, Steve Lawrence, Sam Lombardo, Steve McSweyn and Ken Walther) recorded "Midnight Confessions" (Josie) in 1968. It was written by their manager Lou Josie and can be found as the first track on the second side of "7 Do 11".
That's Carol Kaye's bass line on the opening of The Grass Roots (Rob Grill, Warren Etner, Creed Bratton and Rick Coonce: group members varied greatly through the years) cover which hit Billboard's top five in 1968. Steve Barri produced this with the group and members of the Wrecking Crew.