broken up abroad. Class 37/9 In 1986, four Class 37s, numbers 37150/148/249/124 respectively, were converted to test the Mirrlees MB275T engine and Brush alternator for the proposed Class 38, and were numbered 37901–904. These were followed in 1987 by 37905/6, converted from 37136/206, which were fitted with the alternative pairing of a Ruston RK270T engine and GEC alternator. All six locomotives were fitted with new bogies, and had ballast weights to increase their overall weight to 120 tons. Although intended as a testbed for the proposed Class 38, the two power units fitted were those considered for the Class 60, which was eventually delivered with an enlarged version of the Mirrlees MB275T. They all had modifications similar to that of Class 37/7, including new nose grilles, removal of the central bodyside windows and 4 fire extinguisher ports. However, 37901-904 had a heavily modified central roof section, consisting of flat panels rather than the curved sheets of the original. All 6 had a new exhaust port fitted, replacing the two of the original design. All six Class 37/9s were delivered in Railfreight Grey livery, later receiving 3TG metals sub sector livery, and operated as part of the British Rail Heavy Metals sector, being based in South Wales and hauling trains normally rostered for the much more powerful Class 56 such as the Port Talbot Steelworks - Llanwern Iron Ore tipplers. During the late 1990s, use of the Class 37/9s declined due to availability of the newer and more powerful Class 66s and problems maintaining such a small number of non-standard locos, with all six officially designated as being in storage in 1999. This was not, however, the end of the sub-class. In July 2000, 37906 was designated as part of the EWS heritage fleet but has since been sold into preservation, joining 37901 and 37905. 37902 was sold to Direct Rail Services in 2003, but was scrapped and cut up in 2005 after a review by DRS. 37904 was cut up at CF Booth's in Rotherham in November 2004 and 37 903 was scrapped at Crewe Diesel TMD in April 2005. 37901 has since been sold to Europhoenix and returned to service (complete with its Mirrlees Pioneer name). 37905 was purchased by UK Rail Leasing and is presently stored at its Leicester depot. In October 2019, 37906 Battlefield Line Railway was sold. Operations British Rail During their service on British Rail,