ford 201 casting number

[tduf]

I have a 201 with a cracked cylinder.my casting #E2NN6015.
I have been looking for another block to rebuild i found one with E2NN6015AA.Does any one know what the AA means since mine does not have or which will interchange
thank you Tom

 

[Opti-Mist]

The "AA" is the 26th change to the original "A" drawing. The suffix changes each time the drawing changes. The changes could be very minor or significant. Suggest asking the parts guy at the nearest dealer.