My friend Clyde King has done a significant amount of work on the two heavily rebuilt Rivarossi HO scale Krauss-Maffei ML-4000 diesel hydraulics he's been working on -- you'll find the other gallery here http://www.pbase.com/espeef5/km_ml4000. One unit will be painted in full Southern Pacific colors as SP 9001 (the unit with the snowplow pilot); the other will be in full Rio Grande yellow & aluminum colors with black Southern Pacific lettering as SP 9022, one of the three units SP purchased from D&RGW in February 1964. The three ex-D&RGW units operated this way for some time before being fully repainted into standard Espee colors in 1965. You can find photos of the 1:1 scale Krauss-Maffei ML-4000s at http://espee.railfan.net/spml4000.html
The Rio Grande (D&RGW) unit, with roof-top mounted air tanks mounted in the middle, is powered by a Sagami can motor connected to a Hobbytown driveshaft system. The truck/gear assembly was custom built by Clyde's brother Jay, a professional machinist. The units will be connected via a drawbar and operate together. The unmotored SP unit will be driven through a driveshaft coupled to the motored unit. The pair was test run on our model railroad club's layout. With some additional weight added, both units will definitely pull quite well.
I will post additional photos after they have been painted. However, to be honest, I like them unpainted since it allows you to enjoy the beautiful workmanship Clyde has put into these. There will be a little more work to do, but they will certainly look cool when completed!
BTW, the exhaust stacks featured hinged flap covers that closed when not in use. The models depict the flaps open, as would be the case when they were operated under their own power. I recently received a few close-up shots of the exhaust and flaps... thanks, Mr. Zenk! Clyde will rework both the exhaust and butterfly flaps to better reflect this new information.
Included in the gallery are four Tom Gray b&w 8x10 photos of SP 9001, 9022 and 9023. The latter two units are ex-Rio Grande ML-4000s, purchased by SP and operated in those colors for some time before repainting in late 1965. They are some of the images Clyde used as reference, in addition to photos published in books and magazines including Trains magazine's October 1961 issue; Mainline Modeler's October 1984 issue; along with various issues of Southern Pacific Motive Power Annuals by Joe Strapac, and Joe's "bible" on the Krauss-Maffei units: Southern Pacific Historic Diesels, Volume 2: Diesel Hydraulic Locomotives.
UPDATE 9/11/09: Added four photos at the end showing Clyde's models with updated exhaust stacks. These were based on newly acquired photos, along with close-up in-person observation on the preserved K-M at the Niles Canyon Railway. The butterfly doors are mounted on an inside stack Clyde made from plastic rod turned down and slipped inside the revised outer stack. Clyde's models will not feature the spring mounted tensioning as they're not seen in photos of the two units he's modeling circa 1965.
UPDATE 1/1/11: Added several photos of the two K-Ms Clyde painted. Note these had their butterfly exhaust stacks removed (for painting), plus the units have not yet been weathered or had window glass installed... that's yet to come.