Last year I was frantically trying to comply with this reg and didn't get much help. Finally I resorted to mounting a schrader valve on one of the fuel lines at the front of the engone compartment. I found this valve (same style valve as on a car tire) at the junkyard ina n older Volvo. Several other cars used them as a way for a technician to check fuel pressure. I've heard of people mounting a valve on the fuel retun line, but I was under the impression that it must be on the supply side of the fuel system. I guess that this is because a racer that was running illegal fuel (and managed somehow to disguise the smell) could hide a "clean tank" in the fender well and run the valve for the test port off of this. I could be wrong. Be advised, if you have a fuel cell, this isn't necessary. Denver( Kansas?) is supposed to come up with clarified language and even diagrams on this. JOE