Both Great Northern and Northern Pacific were frequent users of vestibule
cabs. On the GN, the R2 class of 2-8-8-2s was widely equipped, about half
of the S-2 Northerns and several of the O-8 class 2-8-2s. NP was an even
bigger user. The entire A-4 and A-5 classes of 4-8-4s and the Challengers
in classes Z-7 and Z-8 were vestibule equipped. Granted the Canadian
roads had even more inclement weather to deal with, hence the wider usage,
but the all-weather cab was certainly not unknown in the US.
On the GN, vestibule cabs seem to have been applied and removed to
no set pattern. Different dates would see different locomotives equipped
differently.
