Wrong locomotive. That is an SD40-2. Very operable. The Road Slugs are all in the 2200 to 2300 series. I suppose there is a photo of a GP30 labled as an SD40-2 somewhere.
I have not come across the name "Road Slug" before, and looked it up on Wikipedia: "A railroad slug is an accessory to a diesel-electric locomotive. It has trucks with traction motors but is unable to move about under its own power, as it does not contain a prime mover to produce electricity. Instead, it is connected to a locomotive, called the mother, which provides current to operate the traction motors. A slug is used to increase adhesive weight, allowing full horsepower to be applied at a lower speed, thus allowing a higher maximum tractive effort. They are often used in low-speed operations such as switching operations in yards. At low speeds, a diesel-electric locomotive prime mover is capable of producing more electric power than its traction motors can use effectively. Extra power would simply cause the wheels to slip and possibly overheat the traction motors. A slug increases the number of traction motors available to the locomotive, increasing both the pulling and braking power. In addition the load on each traction motor is reduced, which helps prevent overheating from excess current. Slugs typically carry ballast to increase their weight and improve traction. Large blocks of concrete are frequently used for this purpose, substituting for the weight of the now-absent prime mover. Slugs can be built new or converted from existing locomotives. Conversion has enjoyed popularity as a way to reuse otherwise obsolete locomotives."
Ah, nice try anyway, and it brought up the interesting info about "slugs" railways version. (and not the creatures that eat up your garden; or the round blanks that you try to fool coin-operated machines with, in lieu of real coins...)
IIRC [if I remember correctly]; in the conversion of an old diesel-electric loco to a "slug"; all the housings and casings would be removed and opened up to remove the old engine and generator, tanks, fluids, etc.
The ballast(often concrete) would be lowered on to the frame and secured; then covered in with a simple housing and painted. Often a much lower profile, with all the louvres, radiator housings, fan fittings, doors, etc missing, sometimes even the cab goes, though it must remain handy, as a site, for the necessary connections and wiring to take the Prime Mover loco's power and control systems, air brakes etc; to the "slug's" traction motors in the wheel-trucks.
At a glance in all your pics, your "slug" will stand out somewhat, on account of its looks.
Hope this helps; and do put up the Picture Number here; when you do post the 'slug's picture.
And, I have never seen one in real life, so there you go - have to rely on your photos {;>)
Pat, I do indeed have some photos of Road Slugs and Yard Slugs. You are very correct in your definition of slugs and mentioned about the cabs. Cabs are generally removed for yard slugs and left in place and occupiable on Road Slugs. CSX seem to be the leader in Road Slug conversions with BNSF and UP a little behind. NS has just entered into the idea and have very few comparativly. NS however has lots of Yard Slug conversions and most, if not all, of NS yards have some. So let me dig into my digits and find a few for you.
Or, probably, it is confined to local Yard Service; and all the crews would know automatically ?
Added by Pat Rivers-Bowerman on 01 November 2009.