The success of the Ketterik 564B is legendary, and rightly so. However, the advances in steam locomotive design that have taken place since the mid-1970s, albeit restricted to those countries with the necessary wit and depth of concept, meant that this superb engine could also not stay as it was. Jochann Ketterik had proved the superior thermodynamics of tapered boilers, and his successor, Artur Gorote, was more than ready to apply them. The new boiler fitted to the 564B proved to be an excellent steam generator and complemented the existing running gear and exhaust admirably. All 564Bs received the new boilers as they passed through their next general overhaul. In addition, some locomtives were paired with Vanderbilt tenders, including engine 564BB.009 shown here.