4612 is a rebuild of one of the 4500 cars (Korean War vintage).
They were rebuilt first in the 1970s and then again for the Harbourfront line, but were displaced by the CLRVs. They were allocated to St Clair (Wychwood) division until it closed. I forget when that was.
The first rebuilding changed the front lights (used to have big covers on the dash, now just the little ones with the amber lens) and the little catwalk on the roof under the pole. This used to be a proper walk with 3 boards; now it's a box in the casting -- I think the whole rear roof is a fiberglass casting.