With a major component like a boiler, I'm curious as to how much work was involved in a swap. Locomotives (I think) were not built to the exacting specs as we'd see cars today, and I'm wondering how many holes had to be redrilled etc to swap a boiler? While I get the specs of many items (say rods, etc) should be the same, I'd be amazed that all bolt holes for a boiler would line up without modification. To me, this seems a lot more complicated than swapping out two 350 chevy's...
And to this swap, was #42 a class 56? Would the boiler interchange with #283, a class 60??