I don't think a 351 W was available in '72. It is a 351 C.Relative new guy here. Just bought a '72 XR7 Convertible in Dallas. It's dark blue metallic with blue interior and blue convertible top. It's in really good condition and needs minimal effort to freshen it up! Haven't yet investigated whether the drivetrain is a W or C yet. Will post pics and avatar shortly.
Dean,I don't think a 351 W was available in '72. It is a 351 C.