According to Edith Reiter's 2014 book, this instrument was completed on 25 January 1908 and sold to a customer in the UK.
Howe & Hurd (2004) describe heckelphone #39 as a model 36b. Built in four sections, the instrument can be played with our without the 3rd section containing the tone holes for lower Bb and A.
As of 2020, heckelphone #39 is part of the musical instrument collection of the University of Edinburgh, where it has been assigned inventory number 5702. It was possibly purchased from Heckel by noted English conductor, Henry Wood.
Much of the history of heckelphone #39 remains unclear.
A picture and detailed description of heckelphone #39 can be found here.