Depends on whether the parts are OEM or aftermarket. But most steps I've seen were part of a Cessna kit like the later version one linked below. Perhaps a quick call to Cessna support will get you the kit P/Ns for a 172D then you could start looking for the parts. One word of caution, have your APIA check dimensions of the parts before purchase as there can be a variance in strut and doubler dimensions in the earlier models.
If they're shown in the parts manual for the 172D then they're approved already.
Seen those necks damaged by people using ladders, too. Pilots are used to filling cars that have stout filler necks that will support the nozzle and hose, and they have to be taught that the aircraft filler neck will not tolerate that and the weight will cock the neck and crack the tank next to the neck's weld. Some tanks also have a small protective baffle around the fuel level sender, right close to the filler, and I've found those bent and torn free by nozzles.
FYI: the last place you want to ground refueling equipment is at the nozzle to aircraft tank opening. The whole purpose of grounding the aircraft to the refuel equipment is to prevent a ground connection at the nozzle.
I always taught the guys to have the nozzle in contact with the filler as well as making sure the ground cable is well-connected. But contacting the filler neck is different than letting the nozzle rest in it at an angle so that the neck is being cocked by the weight of the nozzle and hose.