Darryl,
see
this for a thorough examination into the evidence whether the gas chambers in Dachau were actually used.
Conclusion:
"Neither the reports by the U.S. Army, Father Hess nor Sack prove conclusively that the homicidal chamber was used to kill people. Until further evidence is discovered, historians will have to conform themselves with the knowledge that it was technically possible to have murdered human beings with poison gas in that room, and that the room, some 16x16x12ft high, was designed for the exclusive purpose of carrying out such a grim task. This circumstance does not free the perpetrators of their crimes. No matter in what manner the tens of thousands of unfortunate people in Dachau lost their lives, they were murdered as surely as if they had been placed in a gas chamber and asphyxiated with hydrogen cyanide gas. The intentional destruction of human life by whatever means is still murder. It is quite sufficient, for the moment, to demonstrate that the Nazis intended to use a homicidal gas chamber in Dachau, and that they designed, built and equipped such a chamber in the Dachau Concentration Camp."
Dachau was a camp in Germany and is often referred to by the revisionists. There is plenty evidence that the gas chambers were actually put in use in the camps outside of Germany (such as Auschwitz). There are a lot of in depth articles on the site on this theme, go read it.