To say who played on what gets murky.
CK herself and others around in those days explain it away that the producers or the studios who posted the credits often did not note the many times somebody else might have been asked in to re-record a part after the initial tracking, as they fine tuned or tweaked the final arrangement put on the commercial release.
I've read this enough from other players in other places besides the West Coast/Wrecking Crew days to think it's entirely possible. Nathan East tells a story of how after Motown moved to LA from Detroit, and Jamerson finally broke down and grudgingly made the move, he was going downhill from his alcohol problems and Nate had been called in to play over the stuff James laid down in a less than perfect state. He fibbed and said he was already booked, though he's sure somebody re-did that track, eventually credited to Jamerson, not accurate at all. He could not bring himself to record over Jamerson (The idea that a broken Jamerson had to buy a ticket and sit in the audience in the rafters for MOTOWN 25 is so sad).
Then there's a whole 'nother rumor of 'ghost' parts over the years where the band's bassist was too far out of it to work correctly, and after hours a session bassist would be brought in to right the parts. This is often rumored, but no one willing to talk about it in broad daylight. Heard this a lot in the 'hair metal' days.
The ultimate determination of who's on a lot of those hit records has been a subject of much back and forth between CK and others, often turning a bit ugly. Over time, we're losing all those master players from those days and who knows if it will ever be proved about this or that record.
