Ron Stubbins was a friend of Jimmy Anderson.
Background
After the death of Jimmy, Sam and Dean Winchester go to meet with Ron, claiming to be insurance investigators, and ask about the black truck. Ron himself found their questions weird and even asked if the brothers knew how to speak English.
Ron's friend, on the other hand, knew about a truck involved in the deaths of black men in the 60s, and hinted that the townsfolk were too racist back then to investigate it properly.