Well due to overwhelming response I will comment myself in case anyone happens by this thread again. I was quite humbled by this body of work on the part of this research group. Gunnar's name went on the book but he gives due credit to several researchers who assisted him in the multi-year study of the subject.
The conclusions reached echoed comments made earlier by another poster on this site that stated while many claim they know what type of instrument was used in Jesus death, we simply don't know. Crucified yes, according to reliable history and eyewitnesses, but exactly what it looked like, is another matter. Neither scripture, nor secular history or archeology support a definitive conclusion. To use upright stake as the proper instrument of Jesus death as the only possible means was irresponsible if uninformed on the part of WTB&TS. Some supporting and biased works may have been used at the time they adopted this belief? Probably and likely. However, but to make the distinction that Jehovah's witnesses adopted in the past on this subject, does not hold up to the scrutiny of scholarly investigation. It was all about making an organization distinct from main stream Christendom ...purely and simply. Some JWs may suggest well it was "by Holy Spirit that this truth was made known". Well, all I can say is goody for you! This mans work in behalf of all who call themselves Chritians was certainly made with prayer and supplication, and an earnest desire for the truth to be known especially since he is a Pastor himself!