Technical Hymer Fiat Ducato 2.5td - Gearbox leak, input shaft seal

[Majemoose82]

Hi all, I’m hoping for a bit of technical help.
I have a 1989 Hymer with the Fiat Ducato 2.5td, I’ve removed the gearbox today to carry out a clutch change.
The gearbox input shaft looks to be leaking and does not seem to be accessible without stripping the gearbox apart. I think the box is a 2HE99.
I’m just wondering if there is any technical info regarding stripping the gearbox? I’m in Preston Lancashire
Thanks