Different Plugs

2002 Windstar 3.8l sport, 97,000km or 60,275m. I bought it 90,000km on it. I changed the plug it had MOTOCRAFT AGSF42EM in the front 3 cylinders & MOTORCRAFT AGSF42EGM in the back three. Is this factory or has someone changed them and made a mistake. These plugs are definitely not new.
Thanks
Darren

Probably the factory installed plugs are what you found.

The Windstar's plugs fire in pairs. They are wired such that one of the pair fires from the side electrode to the centre electrode and the other half of the pair fires from centre to side.

Platinum is enhanced on the electrode that the spark leaves. In order to save money Ford has 3 types of plugs:
Ones with centre platinum
Ones with side platinum
and ones that are platinum on both electrodes.

They install the single enhanced versions in the factory in the correct locations saving in platinum costs. They will only sell the consumer (and dealerships from what I understand) the double platinum types so that it does not matter where they go.

Always use Motorcraft or (Autolite) replacement plugs as they are the only ones that offer the platinum on both electrodes.

My '01 was the same way. I put Autolite double plats in.

thanks
Darren