Yep that how the LR/Santana bug bites! Enhorabuena!!!
Nice one you got there, might even have the HD chassis. Do you have pictures of the interior and from the back?
You injector washer are leaking and you loose pressure in the system. Replace them and youre good to go. Not a DYI job. You need special tools to remove injectors.
I owned a '93 Ardennes Green SWB RRC, a sofa on wheels...it's great in stock condition but it definitely needs a rear diff beef up.
I don't know if a rear True Track is going to work correctly with the viscous center diff...