[scooder]

Another thing to be aware of is that pin. Usually a sheared pin is an indication of a pin that's too hard. It should be a soft pin, hard ones shear. The pin doesn't transmit any power, it's just there to stop the drive shaft moving backwards and forwards.
Of course your pin may have been soft and got sheared due to the excess movement of the two apparently heavily worn splines. A hard pin is a relatively common mistake.
The pinion splines definitely to worn? That would be a shame.
Martin.