Those trucks are more closely related to PCC Trolley trucks than subway car trucks. Very interesting outboard bearing design they have.
That's bc the most of our old fleet I-E; 4000,6000,1-50 > (all built in the PCC era) and the 2000 series cars all had interchangeable parts with the PCC trolleys and the 2200 series was no exception. Although it was the last series to have that truck design. That design would prove to be an epic-fail bc they were made with heavier materials,so intern wore down faster.
Those trucks, nearing their life's completion, would begin to ride rough and be in need of a massive overhaul. Which is why CTA wanted them. This was a back-door attempt to save future $$$ They had a large surplus of parts seeing all the PCC cars we had left over in the graveyard. (Skokie Shops) The major problem, something CTA didn't plan for, was that our system,(built like a subway system for lighter railcars), had begun to rapidly deteriorate due to system neglect in the 70's/80's.
It had gotten weak over the decades form all the heavy equipment in the system and those trucks were the nucleus of the most of the damage. So they tried a different design (which is what we have today) that would soften the blow of the rail car's weight to the structure and tracks. Still, without them repairing the damage that had already been done, it was too little too late.