Here is an extract to demonstrate the difference between the orignal version
of Gear Selector Drum and Selector Forks.
Note the original "Mushroom" shape of the Selector Fork engaging dogs,
compared to the plain, and more robust shape of the modified Selector Fork :

Here's a Photo of the modified Selector Shaft and one of the Output Selector Forks :

The Detent Springs for the Gear Change mechanism are also changed as shown below :

