The back half of CTA 4391 is unique among PCC cars. To the left is the treadle-operated center door. The back of the car includes, on the right side (photo left), a triple set of blinker doors for passenger entry, with a panel under the back right window which contains the cars backup controller. Under the back left (photo right) window is a bench seat which wraps around and ends at the conductors booth visible in the upper-right portion of the photo.