Not to say Herb is wrong but I have some corrections. Stay with me this is going to get long.
RGS smoke box fronts
42 appears to only have had 2 smoke box fronts that we know of. The cast one with the trim ring and the flat plate steel. The plate steel front was fabricated just for 42, so was 41s. Most likely the cast fronts were cracking from decades of heat cycles, and or being removed every tube job.
RGS 40 received 25's front when the 25 was cut up in 1940. Note the blemish under the number plate is the same. Also note the 4 square head bolts at the 12,3,6,and 9 o'clock positions on the door. These bolt hold a large casting that helps insulate the large cast door and also helps break up cinders, more on that later. 22's front had the 4 bolts as well, 41 and 42 do not. 22 and 25 had the hinge straps riveted on the door, where as 41 and 42's are welded.
Here is a photo of the Schenectady smoke box front. Pretty different from what 20 has today.
Here is 20 today, and a photo of D&RGW 278 for comparison. What 278 has is the original 1880's Baldwin style front. They are very similar, the surround is the same but the doors are different. I believe the D&RG(W) started casting there own version of these, this is what 20 has now. Along with other locos like 168(the door at least),268,318,340,and 346 today. Many other D&RG(W) locos had this newer front. The newer fonts for the smaller locos were cast kinda one size fits all, and machined down to the appropriate diameter for each specific class. For example 20's is larger than 346's and has the mounting bolts further from the door.(You can see this on 278 as well) 20's also has a nice rounded edge and 346's is rather sharp from machining.
Jeff Taylor
CRRM curator of equipment and rolling stock.
Edited 2 time(s). Last edit at 02/09/2020 12:47PM by Jeff Taylor.