It does exist on 12" but this is the Tom Moulton remix from the 1977 album "Philly Classics". The 12" came out 2 years later in 1979 -
Back to Frankie Crocker .
I don't know if this was the O'Jays single you had but... this was how some (Atlantic, Columbia etc.) U.S. companies released
extended versions before the 12" format was used.