Does a 9" cougar rear end bolt up to a 68 mustang?

Hey so I'm looking into swapping my rear end out of my 1968 mustang base and I found a guy who has a 9" rear end out of a 1969 cougar for 200$. I just wanted to know if it would be a direct bolt in? He also has a 8" out of a 1967 cougar but I'm not sure what the 8" is rated for since I'm going for 400-450 horsepower and I'm not sure if that's a bolt in as well. Any help is appreciated thanks.