fucking bollox

my gearbox is noisy as hell it sounds like its a cv joint gone you know the sound!!!but it is deffo coming from box

if i engage the clutch it does not go away only if the car is at a stand still?? could this be bearings

diff? or is the box most probabal fucked

also i might sound dull as fuck but the box is a rebuilt BC box with an uprated lsd and 1.8 diesel final drive

whats the 1.8 diesel final drive all about

need some urgent help as i have to change the clutch to but dont know what the fuck to do with the box