[leak between gearbox and tranfer case]

Its EP90 (transfer box oil).

[leak between gearbox and tranfer case]

Defender TDI 90 - 1995

I recently did a overhaul of my gearbox (R380). After we put everything back in place, I noticed a leak between the gearbox and transfer case.

On this initial job, we did put a new collar (original Land Rover part number: FTC4021) and oil seal (part number: ICV100000).

Because the source of the leak seemed to be between these two parts, they were replaced yet again by new ones, however after a couple of days the leak is back.

Anybody can give me pointers what can be the cause or what can be done?

Regards