It was an aftermarket part. They are made by a company named Amco. I never liked the look of the front bar, but the rear bar was cool. I had one on my ex 71T for a while. here is a pic of how it looked.
There was a set on the SReg for sale a few weeks ago. Here is the link http://www.early911sregistry.org/for...ar-set-911-912