My understanding was that alot of works eventually credited to Jamerson may have been done by Babbit, since he was pretty much the fill in if Jamerson didn't show up or was too wasted or whatever that day.. I don't think you are every going to get 100 certainity on many of the tracks.
Bob Babbitt recorded for Motown for approx 2 years 1969-70. Before that Tony Newton was the other bassist at Motown 1964-68. There were others working for Motown sporatically but Jamerson was pretty much it from 1961-1972 (in 72 Motown moved to Los Angeles).
