According to Edith Reiter's 2014 book this instrument was completed on 14 May 1956 and originally sold to a buyer in Germany.
Howe & Hurd (2004) describe heckelphone #4918 as a model 36 cons.
As of 2004, heckelphone #4918 is located in Düsseldorf, Germany, and owned by the City of Düsseldorf. Since 1987, it has been played by oboist Ulrich Brokamp in performances with various orchestras, including the Düsseldorfer Symphoniker, Deutsche Oper am Rhein, Oper Köln, WDR Sinfonieorchester Köln, Staatsoper Hamburg, Staatsoper Berlin, Sächsische Staatskapelle Dresden, Nationaloper Warschau, Teatro la Fenice Venedig, and Orchester de la Swiss Romande Genf. Considering that Strauss's Elektra was first performed in Düsseldorf in September 1956, it is likely that the City of Düsseldorf acquired heckelphone #4918 directly from Heckel.