I lost count....
Bass Guitarist Donald Dunn, as part of Booker T. (Jones) & The MG's, had his hand in just about every major Soul track coming out of the South in the 60's & 70's. Booker T. & The MG's were one of the 4 great studio bands in modern American history (covered Stax Records in Memphis). The other greats were MFSB (Philly Int'l & Gamble/Huff), The Funk Brothers (Motown), and The Wrecking Crew (Motown & others).
Chuck Brown & The Soul Searchers (This one was ripped by Eric B. for "Paid in Full". Sampled the Hell out of him. A bunch of others used his stuff over the years. Wonder if they got paid.)
Ralph MacDonald (died in December) See credit list.
Songwriter, producer, arranger and one of the leading percussionists of the 60's, 70's & 80's. Suggested listening: 'Mister Magic', 'In The Name of Love' and just about anything on list of credits.