1967 Camaro Upper Control Arm Bumper

[red67]

Below are pictures of an original 1967 Camaro upper control arm bumper from my 75,000 mile car on the right and a replacement GM bumper on the left. I purchased the replacement from a GM dealer in May 1998. Both of these bumpers have casting numbers on them of 384220. The original also has casting numbers of FO-63 and the replacement has a casting code of AU 107. Are these date codes? Both appear to have bases of 1.8". Did the original bumper start out life looking like the replacement and collapse to its current state? If so it sure seems like a lot. I'm just trying to make sure I use the correct part for replacement.