Postwar AF Locomotive construction

[BeausDad]

Tried posting this question yesterday but my login/pw info is all messed up so I reregistered.  My question relates specifically to early 300-series Atlantics and boiler construction: Doyle refers to a Type I and a Type II with the  primary difference being that one is a 4-piece boiler and the other is a 1-piece boiler.  I have a couple of 302AC units and the boilers appear to be the same construction except that one has an opening for the Reverse lever but the Reverse is in the tender - possible replacement I guess.  At any rate, could someone explain how I can determine if the locomotives have 1-piece or 4-piece boilers?  I appreciate any input.

[rrlineman]

4 piece means the boiler, the boiler front, the cylinders and the pilot is all seperate pieces. this was made from 1946 to late 49. ( A carry-over from the prewar 565) 1 piece means all 1 casting. if a boiler was needed for a 300, then the slot for the e-unit tab was milled open. if a 302 then the slot was left close. Also the 4 piece 302 had the nicer valve gear from the 300. the later ones had the cheapo stampings for the valve gear. After a certain point only plastice replacement shells were advailable. Yet the dies still had the spot inside to show where to cut the slot for a 300 loco's e-unit lever if needed. All 302AC's were made with a 1 piece shell. If you have 1 with a slot, it may have been a factory replacement shell or someone just sprayed over the 300# and restamped it with the 302AC mark.

[Laurastom]

Some additional info. The easiest way to recognize a 4 piece Atlantic boiler is all 4 piece boilers have wire handrails. One piece boilers, die cast or plastic do not. There were many 4 piece 302AC Atlantics made, I have several in my collection. They were 1948 production.

[BeausDad]

Thank you so much for your thoughtful and thorough reply.  I can now state that both these 302AC units are single piece boilers.  Also, the motor and chassis assembly are loose in the one with a slot in the boiler so I suspect there was a boiloe change at some point.  I really appreciate your time in responding to my question!

[BeausDad]

Thanks - I have learned so much from the 2 rsponses to my question.  I also thank you for your time and thoughtful response.  Your input further confirms that I have a 1-piece boiler as the handrails are cast in, not wires.  Thanks!!!