Yeah, I fianlly found out, years after I moved to California, what the loops on the #7 line were all about!! Identra, wasn't that the system name?
The cars I remembered on the 42nd Street Shuttle were definitely NOT the 1938 WF Steinways -- the cars I'm thinking of had end vestibules like the Lo-V's, but somehow were different. I have all the books on NYC subway equipment, and I still can't figure what they were. But they were "different" than the Lo-V's that we rode into Manhattan from Flatbus on.