Modification of locomotive

[Railhead]

I was wondering what this blue box is, on the side of this GE C40-8W locomotive. Does anyone know?

http://users.adelphia.net/~rwasiczk/DSC_6714-1.jpg

[GN 599]

Thats the heating/air conditioning unit for the cab.

[conrail_engineer]

Correct. It's painted a brighter blue because it was taken off a Conrail unit.

CSX likes to play Mix 'n' Match with locomotive parts. It leads to some odd sets...it's funny to get at the control stand of an SD-50 and find a transition lever; or switches for a heated windshield when non was installed, ever.

But that's CSX...they have their own mentality.

[Railhead]

Thanks for the info