Two trailers (59458/66) were acquired by the Railway Technical Center (RTC). They 975993 / 975964 and used as fire test vehicles. They were scrapped in 2/86 and 7/88.
DMBS 51156 was also destined for departmental use, and spent several years in York Wagon Works awaiting conversion. This never took place. It's engines were removed for use in Class 127s during a power unit crisis. It was scrapped in 1984.