72 Nova exhaust manifold cast dates used?
 

Guys do you know how close the exhaust manifold cast dates were close to your car build date? My 72 Nova SS was built 2 week in Feb 72. I found a good pair of used correct exhaust manifolds with tubes for a Cal built car but the cast dates are J-81 translates to Oct-8-1971. Would these cast dates be used for a Feb-72 car build? Thats about 3 months earlier they were cast and three months before car was built. How close did Chevy use cast date exhaust manifolds?