Gearbox leak

[Rascal]

Trying to trace a leak from my. Manual 5 speed box. Pulled off driveshaft to be met with an oily mess.
The leak had basically filled the. Cv boot and made a lovely mix of gear oil and cv grease


Cleaned up and replaced the "driveshaft bung"
Its a tight fit. Is it supposed to seal the gearbox oil in. As its a flat edge and not as id think lipped seal?
Ps thats the old one...

[Aidan]

yep the flange cap keeps any oil that has wept along the splines of the flange from getting into the CV and contaminating the grease; if the cv is or has been badly worn or not articulating properly then you get a bit more wear on the flange and differential splines, also if someone has previously had the flange off, say to replace the flange seal and fitted the belville washer upside down to make it easy to get the circlip on then the flange isn't fully secure and wear can occur