Definitely the MT75 gearbox. Richard is right that the Mazda box was fitted to 2012 model cars onward but as it’s a Morgan there will be some 2011 cars with it but not before.
My 2011 plus 4 has the Mazda box. Certificate of Conformity is dated 23/03/2011 so it may be one of the first to get one.
To confirm, as well as concentric rings on the bell housing, peering in under the bonnet from the driver side, there is a barcode label on the gearbox casing itself with N7S showing up in large type.
