AWD Transmission: Bevel Gear oil leak

[ianu]

Hi All,
Been a while since I've had to request some advice on here, but it's not something I think I've come across before on here to date.
I've got a significant (both ends apparently) oil leak from the bevel gear housing. First spotted with a pool of oil on the drive. Filthy reddish brown colour. My garage has confirmed it's not power steering or gearbox (manual box) fluid and that initial inspection confirms bevel housing oil is low. Short test drive after cleaning the whole area re confirmed a substantial leak from around the housing.
Question before I start looking for a replacement bevel gear: Is there a seal kit for this, or is it the whole unit? - I know they're only exchange from Volvo if the shaft is toast.
I assume the seal kit supplied when the spline sleeve is done is for the gearbox shaft?
It's all got to come out anyway to sort it so I might as well do the sleeve and these seals anyway - but am I looking at an exchange bevel gear? This one has done just on 90k miles.

Cheers
Ian.