Re: class 56/60 wagontop boiler

I believe the first 60 (#22 Alamosa) was delivered with a wagon-top boiler. It was built in 1877 and pre-dates the first class 56. The first two class 56 locos (#24 Mosca and #25 Hardscrable) were listed with wagon-top boilers on the Baldwin spec sheets.
The details from the spec sheet are: "Material: Iron 3/8", Bill 344 1/2 Diam., 46" Plan: Wagon Top Domes: No. One, 28" Position: Over Fire Box"
The spec sheet for #44-84 (all class 56) states: "Material: Iron 7/16", Bill 521 Diam., 48" Plan: Straight Domes: No. One, 28" Position: Central"
So, it appears that the boiler was 2" smaller in diameter and used 1/16" thinner iron with the wagon top class 56, so weight was probably the same (thus still class 56). The steam dome was apparently farther back ("over fire box" would put it on the large course, and right in front of the cab).