No, not the Mustang. The original Mark 22. In 1958 Al Mooney designed the only two-engined Mooney, which he based on the Mark 20. Called the Mark 22, it never entered production and the prototype was eventually scrapped. In 1966, Mooney reused the M22 designation for their pressurized aircraft called the "Mustang" of which only 30 were built.
It looks like it was based on the Rangers fuselage.