Not sure if this is a worthy addition but I've been led to believe that if you remove the Thermostat (housing???) on the 147 GTA you can see the impellor so it's a fairly easy way of telling if the impellor is metal or plastic, I've also been led to believe that the GTA DO have a mix of plastic and metal out of th factory and it's a very odd situation that can only be checked easily by doing the above.