Not included in the drawing? Sorry about that!
Yes, I have seen some folks complete the connection from the regulator tube to the smokebox bush by having a "joggle" in the tube that goes into the smokebox bush.
The above mentioned link is for the connection of the small tube of the regulator to the smokebox, The method described in the article works well. I have used the compressed O ring method for this connection using a Viton O ring. It has the highest temperature rating.
Attached should be a photo of the smoke box of my boiler that uses this type of connection to the regulator tube. You can just see the end of the tube in the center of the bushing. The gap between the tube and the bush is where the O ring goes. This entire assembly slides into the smoke box end of the boiler. The four small holes in the part that compresses the O ring are for the screws that pull the assembly together.
The threaded fitting out of the side is for the snifter valve connection.
Below that is the wet header, the super heater elements and then the hot header. On the left side of the hot header you can see just a little bit of the pipe that feeds the cylinders.
David

Edited By David Wasson on 15/02/2018 20:25:15