The problem they are having with AU's is called Thermal Shock. Yes, they drill a ~2.5mm in the thermostat to reduce this problem, it's mainly on AU's with aluminum cored radiators, although it does effect cu/br ones too, just not as fast. Also, they will prbably bend down the top corner of the condenser side plate to get more air to the affected bits of the core. If u are unsure if ur car has been done by ford, one of the thermostat housing bolts will have a stripe of orange paint on them..
p.s It is poor work to leave coolant on ANY paint as it can damage to the paint. Always wash coolant of paintwork straight away!!