Interesting that you bring up the switched boilers. For reasons unknown, the boilers were switched during a time when both engines were in for an overhaul in the Burnam shops in Denver in 1887. Needless to say, the NCNG #8D&RG #283 (Baldwin #6057 1882) went on to a long and successful carreer even though fitted with a boiler that was 2 years older.
The #42, the Anglo Saxton (Baldwin #4938 1880) also had a great carreer. It went on to become Silverton Railroad #100 and its remains lasted until 1923, though it hadn't seen service since about 1910.
Regards,
Don F.