I copied this from a previous post a few years ago when I was interested in shopping for a Original.
ID Repop vs GM
Isn't there a injection plug right in the center of a GM one?
YES!
Originals weight about 12 lbs, the repros weigh about 20 lbs. Real ones are almost exactly 3" tall while the repros are just over 2 3/4" tall measured across the back of the bumper from lip to lip. Repros are more flexible the the originals (softer urethane), theres also a difference in the tabs the the center brackets attach to, the bracket consists of two metal tabs next to each other, one about twice the width of the other, but at different heights to match the bracket that attaches to the frame rail. On the repros both of these brackets are square, while on the original bumpers the larger of the two tabs has an angled cut on the edge furthest from the bumper, and it also has a circular notch cut out of the smaller of the two tabs, the repros smaller tab is just a rectangle, the repros have a square notch cut out on the edge of the larger tab, next to the smaller tab where the tabs meet.
This is a GM replacement from the early 1970s. The urethane is yellow , the only reproduction i have seen the urethane was black .
