Note: The gasket shown above has been temporarily discontinued by the manufacturer. You will receive the 280ZX version, which has a slightly wider opening (shown below), which has proven to work just fine. These have been used by many on 75-76 280Zs for many years without any issues. You can see the 280ZX listing on the 280ZX page.
This is the gasket that goes in between the head and the intake and exhaust manifolds.