with what the man done said.
In 64 and 65, the GTO was actually an option package on the Tempest/Lemans and not a separate model. Which is what the '237' prefix on the VIN indicates. Finding out if this particular car was built with the "GTO package" will require obtaining the build records from PHS.
The GTO became a separate model beginning in 1966 and had a different VIN prefix, 242, at that point.