Date code on stock exhaust manifold

On a '69 340 cuda, fender tag indicating build date 02/26/69, engine casting date 12/10/68, what date would you suspect would be on the stock exhaust manifolds? I've been trying to make mine out but they are too weathered. TIA
Does it have headers and you are thinking about switching back to original? Just curious. Or are you are questioning the manifolds you have on there now. A few photos my help us identify them.