There is a diverter/extension on the stack that is in the stored position in every photo i have seen. It looks like it was held in place with two bolts that would be loosened to raise it and could be removed to reposition it to point left or right. Mine will do the same thing.
The extension was made from sections of pipe welded together to get the bend. I turned my pipe from 3/4" bar stock. To cut it into wedge shaped sections, I first turn a wood dowel to a tight fit inside to keep it from getting bent when I cut it and then using a spacer to set the angle, I cut them on the table saw.
They are then silver soldered one by one to make the unit.
And the finished product is laid next to the photo of the real one.