I remember those single rear axle Towers. Slow as Crap, double clutch and wait to get up speed. When I was at TL 131 hated having to get a run up the hill to Park Slope,had to down shift crossing 3- 4 - and 5th Ave for traffic just as you got up to speed.
TL 135 has the ‘hockey’ door installed on the side riding positions. That was after tragic accident when Ff. Smith was killed falling off TL 7. Immediately after, the job installed seat belts you were supposed to use while standing on side positions, than they added a bar that latched to the cab. Finally putting the half door in the picture. Takes a death to figure out something, as usual.
Maybe that was when the job stopped riding the back step?