Bearing retainer nut VS800GL final drive

Hi All, 
 I have a slight oil leak on my final  drive housing, I've ordered a new seal and O ring to fix it over the coming winter as its only a slight weep, when I took the assembly out last year to grease the splines I noticed that there's a nut with a castellated outer [ item 3 in the parts book ] that will need to be removed, has anyone removed this without the special tool required ? and failing that can anyone point me towards such a tool ? I enquired at my local dealers if they had the tool if I dropped the unit in but the guy seemed to be having a no-can-do day so I assume if I want to tackle the job it will be without the dealerships assistance.

Hopefully link to One drive parts page attached below, ignore the reference to Sachs 800, its the exact same unit.

https://1drv.ms/u/s!Ah1SaxFVfigOjR4csvvjK-UjkegS?e=YyanQd