Class 37 - RF Construction - 37414 - DCC Sound Fitted37414 Railfreight Construction The introduction of Class 156 Super Sprinters on the West Highland from January 1989 and on the Far North Kyle lines in the May triggered an exodus of Class 37 4s to freight work. By the end of that year, Laira, Motherwell and Tinsley had gained allocations, while Immingham and Thornaby both acquired three locos each in the middle of 1990, by which point half the sub class were south of the border. One of these was No.