Hi again,
I neglected to mention the gear box numbers are 717-761 (I am 99% sure from memory, will check again tomorrow).
I will take some pics tomorrow of the whole thing ripped down. There is literally nothing in them. 5 gears in the transmission side of things and a further 4 in the trans-axel. I suppose this is what makes them so indestructible and easy to service!
Regards Jay