I was looking at several GT Corral's I have and noticed some easy ways to identify a Ford replacement from what I believe are OEM. I bought the replacement in the mid 80's from Ford and the other two I picked up attached to OEM light bars so assuming they are OEM as well. It is usually difficult to tell OEM from replacement while bolted to a grille but there are a few obvious things on the corral. The easiest is probably the smooth transition edge on an OEM compared with the lip found on the service replacement. If your fingers will fit, a solid piece of metal for support on OEM compared to ribs on service replacement is another easy one. I have no clue how repro's today stack up.
If you have access to the back of the horse, FoMoCo logo makes it obvious for OEM.
