Rekonstruktionslokomotive
The German term Rekonstruktionslokomotive (abbreviated to: Rekolokomotive or Rekolok) meant 'reconstruction locomotive' and was introduced in 1957 by the Deutsche Reichsbahn in the GDR. The term was used for classes of steam locomotive that underwent considerable rebuilding in order to improve performance, rectify design faults and redress wartime austerity features. At the same time, repairs were carried out. The 'reconstruction' included, as a minimum, the installation of a new high performance steam generation system. Consequently, a characteristic feature of these "Rekoloks" is a combustion chamber boiler with rectangular mixing chamber ("Mischkasten") in front of the chimney. On individual classes  (Class 58.30), completely new driver's cabs were built, instead of just fitting the new end walls needed after the boiler had been replaced. The worn cast cylinder blocks were sometimes replaced by welded cylinders. Unlike the Deutsche Bundesbahn's conversion programme, the boilers were not matched to the individual locomotive classes, but the locomotives were matched to the new boilers. The price paid for the easy interchangeability of the steam generation system thus achieved, was the extensive changes now required to the locomotive frame. Also reconstructed were selected vehicles of those locomotive classes that could not be done away  with and from which a long period of operational life was expected. The first "Rekolok", number 50 3501, left Stendal Reichsbahn repair shop ("Reichsbahnausbesserungswerk" or "RAW"), which had carried out the work, on 12 November 1957. The first "Reko" 50, from then on designated as Class 50.35, was assigned to Güsten locomotive shed ("Bahnbetriebswerk" or "Bw"). With the delivery of 01 535 by "RAW Meiningen" on 31 May 1965 the "Reko" programme was initially declared as finished, but in fact it wasn't. For in 1968 the state and party leadership of the GDR tasked the Reichsbahn, to produce a  strategic reserve of 45 Class 03 express train locomotives with an 18-ton average axle load. From 1968 to 1972, not just the required 45, but as many as 52 locomotives of this class were fitted with "Reko" boilers in "RAW Meiningen" from the largely retired Class 22 (formerly Class 39, Prussian P 10) engines. The Class 58.30 "Rekolokomotives" were, due to their age and the very extensive repairs and work required on the donor vehicles, the most expensive conversions of the whole programme. The following normal gauge steam locomotive classes were reconstructed by the Deutsche Reichsbahn and regrouped into  a new class or sub-class: and as individual vehicles for experimental testing and, sometimes, trials equipment platforms: The "VES-M Halle" in Halle (Saale) was responsible for the reconstruction programme