BNSF Dash 9 with strange exhaust stack

[eolafan]

Today while "fanning" the BNSF Eola yard I caught a glimpse of a BNSF Dash 9 unit in one consist (could not get a photo as it passed by too quickly).  This unit had a very unusual exhaust stack and was not your typical GE oval stack which typically stick up about a foot from the car body...this one seemed to have a large "box" built around the original stack and seemed to protrude about two feet or more above the roof line of the unit.  Can anybody give me a clue as to what I saw today? Thanks.

[Kielbasa]

Sounds like one of the new Tier 4 ET44s. We just got a bunch of them in the yard the other day and they all have some shrouding around the stack, so much so you can't even see it. The radiator also sticks up quite a bit more than on a Dash 9. A unit number would help if you by chance remember it. 

[kgbw49]

A couple of possibilities...

Here is an early series ET44C4 with the "box" around the exhaust stack...it is not necessarily two feet higher than the motor compartment but it is a pronounced step up...

Or perhaps more likely, it was an AC44C4M which is a C44-9W converted from six DC traction motors to four AC traction motors...

[pajrr]

It could also be a spark arrestor. Diesels can give off sparks, too.

[beaulieu]

It is quite rare for a turbocharged locomotive to be equipped with a spark arrestor as the turbo is an effective spark arrestor.

[FlightPlan]

We have had several of these in our shop over the last few months. It is just basically a metal box that mounts around the stack to hold a plate over the stack to block it off for storage. Once out of storage they just leave the box in place instead of removing it. A little more sturdy than the vinyl covers we used to use. 

[ATSFGuy]

Are the Dash 9's still in service or retired?

[CSSHEGEWISCH]

They are still in service.  I see them regularly on the east end of the Transcon, often working with GEVO's and Tier 4's.

[NorthWest]

A bunch of the 600 series are out of storage, too!

[WindyCityRails]

I may know what you're talking about. I've been seeing photos of Warbonnet and H1 Dash 9s with what looks like a rain guard. They may be going into storage. What was the paint scheme?