I used to go to high school in Agincourt which would see me at STC every AM. Back then they had 3 1975 GMs that were all on the 129 rush hour extra runs. 8034, 8058 and 8111 (last water bumper in TO). There was the odd time one of those would show up on another route. I understand that it was not uncommon to see 8034 (last linen rollsign in TO) on the 85 or 39. Those other routes you mentioned I'm not sure. I basically never saw 8058 post rebuild. In fact, the last time I saw 8058 was at the division when the gentleman Bus Medic mentioned above gave me and a buddy a nice evening tour. I believe this was Dec 2000.
The main equipment I remember on those routes at that time (1998-99) were:
85. '96 OBI V
57 was almost exclusively 96 orion V
131. Anything could show up on this route.
171. This route was exclusively Orion III and was PACKED like you wouldn't believe.
21/128. 96 Orion V although it wasn't uncommon for a GM to show up on either, esp the old 128. I have photos of a d4087 and even an orion III on the 128.
Ok back to GMs...