My 1st ALCO!!!!

I don't know for sure, but the longer than taller radiator (which is tarped in the photo) suggests an S-4. I base that presumption also on the trucks, which appear to be AAR type A switcher trucks. The S-3's radiator would be taller than longer, and the S-2 would be riding on Blunt trucks. So, what do you suppose is the heritage of this locomotive?

I don't know what its heritage is, but I was talking to Paul McCarthy (president of Rarus Railway) & he said that it was being used for switching over in Silver Bow. He also said he it was probably built somewhere around 1939. He said they've rebuilt it several times in their shops for the guys over in Silver Bow. It isn't used anymore because the frame was actually starting to fail. He said Rarus hopes to buy it & fix it up & then put it on static display at the museum. BTW, could it be possible that this is an S-1 or S-2 that got its blunt trucks replaced with AAR type-A trucks? After 50+ years of service, it seems that it could be possible.

Ok, I've been researching this on the web & here's what I've found so far:

It's radiator grills are more like those of an S-2/S-4
It' exhaust stack is like that of a S-2/S-4
It has a couple of taller engine access doors near the cab, like an S-2/S-4
I found out that there was a Union Pacific S-4 #'d #1166, like this one, & it would make sense that this Silver Bow one is the same one as UP #1166, because UP has a line that comes up to Silver Bow, Mt.