BMW Airhead -Drive shaft to Diff - Help needed

[Bushpig]

The teeth of the drive shaft and the gear into the diff. 'ate' each other and I am busy stripping to repair.
For the life of me - and with the great support of Half Daft and his extensive workshop - we cannot remove the nut holding the gear on on the differential side.
Has anyone out there (Freek?) worked out a trick to this removal?
Pneumatic hammer socket, heat plus a very long extension spanner and not a smidgen of movement.

It was a tad full of muck too but thats easy to get rid of.
G

 

[Kneeslider]

 

[eberhard]

 

[Bushpig]

 

[eberhard]

 

[GRAVELTRAVEL]

 

[raffie]