A couple of days ago while driving past YYZ, I noticed a 330 (at least I think it was a 300 - twin engine wide-body Airbus) on final. It caught my eye because it was painted white, with no other visible markings. It's possible I missed a discreet logo somewhere, but it definately didn't have AC markings.

Assuming it was an AC aircraft, I thought the paint shop was in YUL, not YYZ. Can anyone enlighten me about this mystery aircraft?