In 1987, consideration was given to using the class on freight trains. To this end, 50049 "Defiance" was renumbered to 50149, equipped with modified Class 37, lower-geared bogies and outshopped in the new trainload grey livery with Railfreight General decals. It was based at Plymouth Laira depot, and tested on local china clay trains in Cornwall as well as heavy stone trains to London from Devon quarries. The project was, however, not an outstanding success and by 1989 the locomotive had been returned to its original identity. Ironically, the electronic anti-wheelslip equipment, with which the entire class had originally been built and which would have been key to the success of this experiment, had been removed during the refurbishment process.