The Leuchter Report Is Online
If you would like to read Fred Leuchter's report it is available online here -
http://www.ihr.org/books/leuchter/leuchter.toc.html
Leuchter's work was vindicated by Germar Rudolf in his report -
http://www.holocausthandbooks.com/index.php?main_page=1&page_id=2
The Rudolf Report is available free in pdf or html at the above link.
Walter Luftl was the president of the Austrian engineers association and appeared in court many times as an expert witness. He also wrote a report questioning the mass gassing claims. The Luftl Report -
http://codoh.com/library/document/2383/