In the second half of the 1950s, the FS developed a new “standard” diesel multiple unit with the aim of replacing the steam traction and the older, pre-war multiple units in subordinate services.

Even if these were not large or significant traffic, they were of fundamental importance for all national rail traffic. Simplicity of construction, reliability, a significant improvement in performance and comfort compared to previous generations of vehicles have made the new ALn 668 series railcars (with 68 seats and capable of multiple traction) a great success.

785 units were built for the FS, in 12 series over more than three decades.

In addition, there are around 90 pieces for private railways, associated sidecars and hundreds of copies based on them for foreign railways. From the 1900s and 1000s series from 1975/76, the car body was changed; instead of a central entry area, there were now two off-center entry areas. The series 1200 and 3000/3100/3300, on the other hand, were again equipped with a central entry area.

CHARACTERISTICS OF THE MODEL:

• Model with metal frame, 5-pole motor with cardan shaft drive on both bogies of a railcar, two wheels with traction tires
• Set consisting of a powered and a non-powered railcar
• Minimum drivable track curve radius: 192 mm
• Next18 interface (NEM 662) for DCC and DCC sound decoders, prepared for 11 x 15 mm "sugar cube" speakers
• "S" versions with built-in ESU Loksound Micro V5 sound decoder with loudspeaker and model-specific sound
• White headlight and red tail light with automatic travel direction switching, independent control of the third headlight in digital mode
• Possibility to selectively switch off the headlights, in digital mode via decoder and in analog mode via dip switches
• Standard interior lighting on all models
• Close coupling kinematics on both sides according to NEM 355, ex works with standard coupling according to NEM 356