"The Sherman is mechanically identical except it has a new single motor gearbox " That doesn't seem very mechanically similar to any previous version of Sherman gearbox.

The first version used essentially two separate gearboxes and slip clutches to effect turns and the gearbox initially was issued
with change gears that allowed both electric motors to operate on both gearboxes or each one could be operated independently- I still have both gear sets for my original 1975 Sherman..
Discounting various 'economy' versions of gearboxes their penultimate two gearbox setup that just about every maker used was what they've used for years. This latest gearbox uses a
planetary braked differential type of design unless I read their description incorrectly.... that is altogether different....

Jerry