Earl's mentioning of the 346 jarred my memory of where I'd gotten the idea about new smokeboxes. In the book Locomotive 346, the first 100 years published by the CRRM, they describe the reboilering done to 346 (then numbered 406) in 1914.
"The I.C.C. enacted a much stricter boiler code in 1912 and the 406's origninal wrought iron boiler would become illegal under the new law. Major work was performed on No. 406 at Alamosa in 1914. A carbon steel boiler was fitted along with a straight "shotgun" stack and a slightly longer smokebox. The oil headlight was replaced with an electric model in order to comply with a change in Colorado law. In recognition of the excellent care provided to No. 406 by it's regularly assigned engineer, the master mechanic authorized installation of a unique round number plate rimmed in brass with raised figures to replace the standard rectangular iron plate which had been on the engine since 1903".
I checked to see if they mentioned who the engine was assigned to, but the only information about it was that engineer E.J. Freeman was given a 30-day suspension for scorching the crown sheet somewhere around 1905.
Don