I might be able to help you guys. I'm a Chicagoan, I've lived here all my life. I was born and raised in the city, and live in the suburbs now. I ride the "L" trains once in a while, not very often anymore. I used to take them everyday for a couple of years, in the early 1990's.
There are no ready to run N scale equipment for the Chicago "L" trains. There have been some bodies made, where you need to provide your own chassis. You can also use subway equipment made by Kato, Tomix, Greenmax, and other Japanese companies. None of those models are an exact match, but they capture the essence.
Here in Chicago we call the entire system the "L", and have since the 1890's. The first elevated track was build in 1892. Our first subway lines were opened in the 1940's. From this website,
http://www.chicago-l.org/FAQ.html
1.3 Q: Why is it called the "L" TM if it isn't always elevated?
A: The thing to remember here is that Chicago's non-elevated sections are relatively new. Unlike cities like New York, Chicago didn't get its first subway until 1943. Up until this time, most of the system was elevated (with the exception of a few short sections in outlying suburbs, but even these were mostly elevated by the 1920s). So, by the time the State Street subway opened, the name "L" (short for "elevated railroad") had already been in popular use and thus stuck.
However, what is known is that the use of the term "L" pre-dates the opening of the first line in 1892 and was quickly adopted by the press and public. It could be seen on printed materials and painted on the elevated structure at stations by 1893, the year after the first line opened. So it has been with us from the beginning of the system.
Here in Chicago, unlike many other cities, we only call the actual subway portions the subway. The entire system is called the "L".
Also the cars are a little shorter then typical subway cars in other cities. Some of the curves are very sharp. Also from same site,
http://www.chicago-l.org/FAQ.html
4.7 Q: Are the CTA railcars shorter than that of the NYCTA (New York City Transit Authority) or other cities? To me they look a lot shorter in length.
A: Yes, CTA cars are shorter than an NYCT/IRT Division car. Those cars are around 51 feet long.
Chicago's car length was really dictated by the need to be able to traverse those tight curves in the loop and at places like Harrison/Wabash. Remember, these were private undertakings so condemnation/eminent domain was not an option for them, and every curve easement meant buying more real estate.
Each "L" car is 48 feet long and, since 1950, are permanently coupled into two-car married-pair units. I think a longer car might be more useful now, but Chicago has built it's system into a 48 foot-only clearance.
The newest deliveries, the 5000 series of 2009 are:
Car length - 48 feet (14.63 m)
Width - 9 feet 4 inches (2.84 m)
Height - 12 feet (3.66 m)
Weight - 57,000 pounds (26,000 kg) empty
Track gauge - 4 ft 8 1⁄2 in (1,435 mm)
Maximum speed - Design: 70 miles per hour (110 km/h)
Service: 55 miles per hour (89 km/h)