67 Camaro exhaust manifold

[Camaro67ss396]

I have a 1967 Camaro 396, 325hp number matching with 82,000 orginal miles. I also have the protecto-plate. The only code on the motor that does not match is the left side exhaust manifold.
My records show the number LH3856297 is for a 1965 396, 325hp.
Is it possible the factory installed this exhaust manifold?

[ggtsvnv]

  I would think not: it was probably replaced at some point. If your not careful you can crack them removing the bolts to them.