If you really want to spot a reproduction examine the welded on motor mount areas, look at the sides of the fromed steel parts that would be added to form the motor mount bosses. These pieces are generally reproduced using modern day manufacturing techniques such as plasma, laser, or water jet cutting which makes the edges look different that originals which were stamped using dies. The edges of the die stamped pieces generally have a pinch line along the center wher they sheared in the stamping process, the modern edges look more serrated like the edges of a dime or a quarter. This same method can be used to spot many modern reproduction steel parts such as intake manifold brackets and motor mounts.