Thank you Gentlemen: The pictures I have been able to review fail to demonstrate any rivet lines as in Chris' picture. The original blueprints do not state if the stack is to be riveted, welded/soldered or lapped. I have wondered if there was a single row of rivets along the rear of the stack, so as to hide the rivets for aesthetic purposes.
In my "model", (4" scale ) I hope to use a round pipe (about 4" diameter) as the solid stack and place the sheetmetal diamond stack over it, allowing me to alter appearances to my taste.