nissan terrano II slx 2.7td gearbox problem

[dawni007]

hi. my nissan terrano II slx 2.7td 1994 lhd is losing gear box oil. i noticed the gears starting to be a bit stiff and grating. had a look underneath and can see a fair amount of oil it looks to be on the top of the main gearbox but can't see where it is coming from. i need to get some more oil in there before i get it properly looked at but can't even see where you put in more oil. can anybody help?? cheers