In 1967 as part of a short-lived experiment to use the railway to carry container traffic, under the title of Mantainors, a new “R” class was created as below using former pairs carriage underframes, the bodies of which were removed and dumped in the goods yards at St. John's and Castletown; no stock carries this prefix today, the frames having been sold off in 1974 to the scrap dealer Manx Metals, the experiment having ceased in 1968.  The series letter and numbering were non-canonical at the time, being applied by the late Douglas Robinson and Peter Craine, stalwarts of the Association.  The numbers were applied in the order they found the vehicles, not in order of their former carriage numbers.