There’s a complicated set of dates here – recorded in 1973 and released originally in 2012 on CD by Philadelphia International Records and Legacy (Sony’s label for reissues), but then released for the first time on vinyl for Record Store Day 2021.
The performers are MFSB, Harold Melvin and the Blue Notes, The Three Degrees, Billy Paul, and the O’Jays, with an introduction by MC Don Cornelius from Soul Train.
I found my copy in a discount bin at Newbury Comics in the Natick Mall – always worth taking a pass through whenever you find yourself near one.