However, it is pretty hard to provide a differences course if the OEM doesn’t tell you about a new ‘feature’.
I wonder after 5 new handles and four new heads if it is no longer ‘Grandfather’s Axe’
IT IS SO GRANDFATHER'S AXE shout Boeing
Because, if it's not Grandfather's Axe, then it needs to be re-certified against modern standards, instead of being 'grandfathered' (official term!) to the old 1967 certification standards. And that would mean a lot of changes which would be very expensive and make a common type rating much more complicated.
There are those who believe that the FAA has been far too lax in allowing the later designs to be grandfathered, not only on the B737 but also the B747.