CHICAGO (WBBM) – CTA’s newest ‘L’ cars will be reintroduced on the Pink Line beginning Sunday, but you will have to look hard to find them.

Even though CTA has more than 50 of the newly manufactured 500 Series ‘L’ cars on hand, it will begin by running two six-car trains.

Spokesperson Kathryn Hosinksi said the transit agency wants to make sure they are reliable in everyday service.

The cars were introduced, with much fanfare, on the Pink Line in November, but were withdrawn a month later when serious flaws began to appear in steel journal bearing housings that could cause a derailment, if they failed.

LISTEN: WBBM Newsradio’s Bob Roberts reports

The parts, manufactured by the Suifang foundry in Qingdao, China, have been replaced by identical Chinese and German-made parts.

The cars are the first of 706 that Bombardier expects to deliver to CTA between now and 2015. They are most easily identifiable because of the new York-style “bowling alley” seats, designed to allow more room for standees, and because of their destination signs, which are LED instead of the traditional canvas roll signs.

The new cars cannot be mixed with older cars because they are propelled by alternating current motors, instead of the traditional direct current. They are intended to be quieter, accelerate more rapidly and save on power.

Production of the new ‘L’ cars resumed in new York on March 28. They will replace CTA’s oldest ‘L’ cars, the 2200-series cars, built in 1969-70 and in service on the Pink and Blue Lines, and most of the 2400-series cars, built 1976-78.

CTA had 1,190 ‘L’ cars in service before deliveries began. It expects to have a fleet of 1,400 after deliveries and retirements are completed. It is expanding its fleet in an attempt to reduce overcrowding and make it easier for CTA to meet established schedules.