The passenger side can be stock, the driver side used this type of manifold for an A-body. I have a used one in my shed but here is a pic of a clean one. It supposedly dropped the horsepower from 375 to 335 on a stock motor.
There are 3 different passenger side manifolds , the one in that picture is the 68-69 383 manifold . the passenger side can use the std 67-73 HP maifold but the A body unit is different , is got a longer down tube and it angles in toward the block
