I believe the nose cone on the CNR U1fs are of sheet metal construction with 4 bolts on the smokebox door and 4 additional located around the headlight(see pic)
They were all coal fired when constructed at MLW in 1944.
As mentioned previously some of the class were transferred out west to Winnipeg after 1955 and again in 1957 , with all being converted to oil but the later locos retaining their bullet noses with added vents directly below the headlight