Thanks GOLDEN-ARM for the great cab pictures, and the insights from someone who has operated this engine. You are absolutely correct that Doyle McCormack does not and never has owned 644, it is not currently at the Brooklyn Yard, and that it is currently a freight-only SDF40-2. I didn't give the full story (as I know it) before, because this was an Amtrak thread, but now that its an EMD thread, its appropriate.
644 was built as Amtrak SDP40F #644. It was one of several sold to Santa Fe (in exchange for switchers I think). Santa Fe rebuilt their ex-Amtrak SDF40Fs, removing the passenger heating equipment, adding a front platform and other changes, designating them as SDF40-2s (a designation ATSF made up). They lasted long enough for some of them to get BNSF numbers; this one was #6976. Shortly before being retired, it was painted in its current color scheme for the Maersk/Sealand special train, which let it outlast the other BNSF SDF40-2s. After it was retired, Chris Fussell, who had already acquired Amtrak F40PH #231, acquired BNSF #6976. It was moved to the Brooklyn Roundhouse (after some other stops) where it was repaired to running condition and numbered back to 644. It was at Brooklyn for months, maybe as long as 2 years, and was clearly visible from the Holgate overpass (with that paint job it was hard to miss). It left Brooklyn when short lines were willing to lease it. My pictures of it were taken in Lebanon, on the Albany & Eastern, in Sept. 2006. If no one is willing to lease it, it would most likely return to Brooklyn. I know its not there now, and figured, through wasn't sure, that it was on the P&W somewhere.
I'm not certain about 644's reporting marks, as I've never seen it wear any since its BNSF days so I'm willing to accept that it has NRMX reporting marks now. (I assume thats what you meant, as NMRX is the New Mexico RailRunner commuter train) It may have also had DLMX reporting marks in the past. Just because Doyle didn't own it, doesn't mean that he didn't allow it to wear his reporting marks if the real owner didn't have marks of their own. I don't think Doyle personally owns #4449's tool & crew cars, but they have always worn DLMX marks.
As for whether or not 644 is "preserved," I don't think condition matters. There's a lot of "preserved" steamers rusting away at city parks and museums all over the country. 644 was acquired with the intent of retaining it for its historic value, and in my mind that qualifies it as preserved. But, that's a matter of opinion.
Oh, and I think "Powerpuff" is a great nickname for it.