A Federal Express driver reported missing over the weekend was found dead of a heart attack on a rural road south of here. Ronald Etchemendy, 46, of Sheridan, Wyo., apparently died while trying to put chains on his van and dig it out of a snow drift, Big Horn County Coroner Terry Bullis said Monday. Etchemendy’s body was found early Saturday. He had been reported missing several hours earlier when he failed to return from his delivery route. Searchers traced Etchemendy’s route and found his van stuck in snow on Pass Creek Road near the Montana- Wyoming border. His body was lying next to the van, Bullis said.