The Aristocraft U-boat is one of the earlier diesels manufactured by
the line.  The model is actually one of a U-25B with four wheel (B-B)
trucks.  This diesel was manufactured from 1960 to 1966 by General
Electric (GE) Transportation Systems Division of Erie, Pennsylvania.
Starting in April 1960, with the introduction of the "test unit", GE
began the "high horsepower" diesel locomotive tradition that still
exists today.   GE built 476 of these 2500 HP diesel locomotives, and
railroads all across the country ordered them for high speed freight
service.  These 4 stroke engines had a characteristic knocking sound at
idle and low speeds.  As they moved down the rails, they produced plumes
of sooty, black exhaust.  At higher RPM's, the diesel prime mover
sounded much like the 4 stroke ALCO's.
    The Aristo model is quite accurate, though lacking in the finer
details seen on their newer diesel models.  It has two powered trucks,
directional lighting, and smoke.  The end rails and handrails come
separately and must be attached by the modeler.  Aristo knuckle couplers
are standard, but hook and loop couplers also come in the box for those
who prefer this type.  Number boards are lit along with the headlights,
but class lights do not come lighted.  These can be lighted with some
modeling expertise.  All switches for control of lights, motor, and
smoke are located behind a door at the rear end of the locomotive.
    This is a very smooth running model.  It has excellent starting
speed, and will crawl smoothly along the track at low speed.  The one
drawback of the U-Boat is that it is light, and will spin it's wheels
when pulling a substantial length train or going up a grade.  This
shortcoming can be rectified by placing additional weight inside the
carbody.  I recommend about 16 additional ounces, with 8 ounces located
over each truck.  This should give the locomotive better traction
without taxing the motors and bearings too heavily.  I used fishing
weights in mine, but plumber's lead sheet can also be used.
    Kadee couplers can be fitted to this diesel using the Kadee kit #
388 and #830 couplers.  This is a simple conversion to make if the
instructions in the kit and coupler package are followed exactly.  A
bonus with the #388 kit is the inclusion of "filler plates" that fill
the opening in the pilot ends when you make the Kadee conversion.  These
plates can be painted to match the pilot ends, and help to make it more
realistic looking.
    While no one but Aristo makes a specific sound system for the U-25B,
Soundtrax and Phoenix make systems that sound close (they both recommend
the ALCO).  The horns on both systems can be purchased as multi-chime,
which is more appropriate for this vintage locomotive.  There is room in
the fuel tank for a speaker and sound card, and plenty of room in the
carbody for the rechargeable battery.  The conversion is simple and
straight forward, as Aristo has the simplest wiring harness of any
manufacturer to work with.  Of course you can also purchase the Aristo
sound system which comes in a replacement fuel tank, and merely plugs
into the existing harness.  This system is made by PH Hobbies, and is
notable for it's lack of volume and poor battery recharge.
    There are many details out that can be added to this diesel to make
it more realistic.  These include additional headlights, multiple chime
horns, radio antennas, ditch lights, and snow plows.
    A multiple lash up of these second-generation units will look
impressive on any railroad.