Expert Flyer could be helpful to you as they have aircraft equipment change alerts:
Aircraft Change Alert
The Aircraft Change Alert form allows you to create an Aircraft Change Alert for a particular flight. An Aircraft Change Alert will periodically check the aircraft equipment code returned with the seat map of a flight to see if it has changed since the alert was created. If so, ExpertFlyer will notify you as to what the new aircraft equipment code is.
I don't think it can tell new config from old config though?