Are any of Jenkin's crew guys still around, they might remember if the car was an RS when purchased. Given the fact it had a lot of RS content I think it's plausible to think it was an RS rather than not. And the story about the color, Doug Boyce said Grumpy was urged by some photographer to try a different color than white because it was easier to photograph. But then Bill just painted the car white. Since he painted which is known, he might have tinkered with some aspect of the cars. I don't see him adding the rear marker lights but that's just me.
This is the only mention of Bill Hayes I have found:
https://www.billrolikenterprises.com/vintage.php
All of these cool vintage photos were taken by myself between 1966 and 1976, prior to the bulk of my own racing activities. Most were taken at Island Dragway, Great Meadows, NJ, Old Bridge Twp. Raceway Park, Englishtown, NJ, or Indianapolis Raceway Park, Clermont, IN. You will also see a group of unique photos I took during a split, two week stay at Don Carlton's shop in Lenoir, NC, during late 1976 and early 1977. I was assisting local race car welding guru Bill Hayes with fabrication on the Body-In-White Aspen Pro Stock car for NJ Super Stock racer Ed Lukas ("Over The Hill Gang" SS/AA). Don and head wrench Clyde Hodges were working on their other projects, including "stretching" the "Gold" Dodge Colt in preparation for the upcoming 1977 Winternationals, so Lukas wanted to speed up the process and sent us there. A fantastic experience! Sadly, the Aspen was the last car to come out of the Carlton shop, as he passed away as a result of injuries from a testing accident only a few months later.