The photos of the adjustable grates were taken from this smoker 

The photo to the left is of the left door. It shows the openings to the vertical section and the permanent angle iron guides for the adjustable height grates.
The center and right photos are of the right door. The center one is in the lower position and the right shows the bottom grate one level up.

All the photos here are of the right door. The bottom grates is two levels up and.