This from Idaho Mike:
"Sundowner: Your wood box is fine. The side of the wood box with the short side should slide in first. 2 of the long sides will be down the side of the heating element, and the other long side will keep you from shoving the wood box any further back. It should look like this: [ with the heating element in the middle of the [ , and the long side of the [ facing you once you slide it into the smoker."
Hope this helps.