Blinker doors were retained in the post PCC-car era because of their all-electric operation, and the fact that no CTA car built since 1947 has had an air system on it (4000s have air-operated sliding doors). Basically you have electric motors opening and closing the doors in a fairly uncomplicated manner. It wasn't until later an all-electric sliding door system was developed (see: 2400s). Also the 2000s and 2200s share some parts in the door mechanism. At one time those two variants of "L" cars were very similar to one another, aside from the shells/frames being different metal and the climate control being setup differently. Of course the 2000s were never given a mid-life rehab and stayed closer to their original configuration, whereas the 2200s were and have continued to get minor upgrades/new components. Now a 2000 and a 2200 have lots of differences between each other, but if coupled they would still MU.
Molded fiberglass has its pros and cons. It's easier to fix in-house when inevitably a couple cars brush up against one another, but will rot and crack if kept in kept in direct sunlight for too long.
That old car might be worth money!