GK121,
As I write in Post 9 - let's see the true figures on numbers before we get too excited.
When the Mk1s went back to the US for upgrade, the americans insisted that they were all of one standard. A significant chunk of activity ensued as the cabs were modified before shipment. On arrival in the US, the mods were mostly stripped out as part of the pre-update prep work that had been agreed. That's probably the last time 'configuration control' was achieved (Fleet Manager's nightmare!).
Old Duffer