According to the “Traction Handbook: Traction Plan Index #1” there are plans for a few things under “Connecticut Railway & Lighting Co.” aka Connecticut Co., at least as of 1972 when the book was printed…
Several were apparently available from a commercial supplier named John D. Sommers, of Sandy Hill Road, Middlebury, Connecticut 06762, including a 42’ 15-bench open car, a 41’ wood city car, and a 43’ city car.
Model Railroader May 1963. Page 48, has plans for a 42’ wood 15-bench open car, and MR October 1940 p. 532 has plans for a 48’ steel suburban car.
“Traction Heritage” Vol. 3 #2, p. 50, has plans for a 39’ steel cab-on-flat dump motor.
Railroad Model Craftsman, May 1959, hpage 42, has plans for a 41’ wood shear plow. The plans for the shear plow were reproduced in the second edition of Carstens’ TRACTION PLANBOOK on Page 89.
If any of the Connecticut Co. cars are standard designs, you can look for produced models off the shelf–I found one pic of a single-truck Birney model in Connecticut Co. scheme (along with a kitbashed Connecticut Co. car) in TROLLEY TALK #55, Page 5. If they really used Birneys, those can be found on eBay in HO and O scales.
In ERHS Bulletin $47, “Light-weight Cars”, there is a photo of Connecticut Co. #3001, which appears to be a fairly standard double-truck Birney. Ken Kidder imported both plastic and brass versions of this streetcar, which are similarly available to someone willing to hunt–I think someone involved with AMB/LaserKit is working on reproducing the double-truck Birney body in laser-cut plastic but don’t know the details.
I didn’t find anything in my back issues of T&M…