Thats not quite correct ( sorry to be pedantic )
Option 471 was always an option apart from on the performance pack cars which stopped in 2010. The performance pack cars had the diff as standard as part of that package. Its sometimes called the P30 package.
In '10 Mercedes launched a Performance Pack Plus ( note the extra P ) which made option 471 just that - an option. The performance pack plus is sometimes refereed to as P31 package abroard
So
Upto MY10
Diff optional
Came as standard on a PP car
MY10 onwards
Diff optional on all models including the PPP car