Oil leak from top of gearbox

My 90 which has a disco 300 tdi engine and box fitted has developed an oil leak from what looks like around where the lever assembly goes in, is there a gasket or something there that could have failed??

Cheers

Andy

After a bit of investigating whoever had fitted the engine and box had connected up the gearbox breather pipe to the end of the injector leak off pipes so the gearbox had nowhere to vent to so I'm hoping that when i was on my greenlaning day which was probably the hottest day of the year so far the oil had nowhere to expand to and was forced out the top.

More likely your gearbox is full of diesel .............. me thinks you best get under it and check - drain - refill with OIL .

I did think that too but it was connected to the very end of the leak off run next to the bulkhead which appears to be blocked off anyway with something, don't know if it should be blocked off or should there be a pipe on it???