Wreck repairs possibly?
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And the Dash-2 door window by the start switch on the long hood.
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Wreck repairs seems like a good assumption, Jessica.
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The sight glass has always puzzled me.  It seems that most shots of IC/ICG SD40As I have seen show it, but at least a few pictures of lower-numbered As do not.  I do not remember ever seeing a shot of IC/ICG straight SD40s (6000-6005) with it, so it does not seem like a railroad shop alteration.  Maybe an IC/ICG roster pro will jump in and tell us.
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