no, there is no part number. Its not for a 72 240z. thats what I have and if I remember right ,the overider bars were dealer installed items and I think I had to drill holes in the bumper of my 240z to make the (correct) rear overider bar fit. It has been awhile.
I guess nobody knows. I bought these (I have 2) new from a Nissan/Datsun dealership in TX over the phone. They had had them new in stock since the 70's. They said they were for a 240z car and I got them thinking one would fit my 240z. It didnt. When i called them back they said they were just listed as fitting a z-car and wouldnt take them back. This was all about 10-15 years ago and I have been dragging them around with me not knowing what they fit or what to do with them... Any help would be appreciated.....