I'm going to guess here.....the knobs might be, the hinges are not based on the chipped out areas around them & the wheels might actually be original, based on the way they are heavily plugged in.....
They kept changing certain things on all kinds of models, sometimes for a reason, sometimes with little rhyme or reason (at least from where I sit) & so some of this could possibly be stock.....are you still able to connect with the people & ask them what they remember about the fix-its?