1989 300se front driveshaft removal

[agarnusa]

I am trying to change my front flex disc which I have unbolted. I am having problems removing the front axle to take the old one off and replace. I have removed the heat shield and see the 46mm nut. If I manage to loosen it how does the shaft come off. I have dropped my exhaust system but removal due to rust is impossible without creating other problems. Is there a way around this - I cannot slide shaft back enough to drop the front off the tranny so I can replace the disc. Any help would be appreciated.