The problem is not underneath the vehicle but most probably where the drains are connected to the tunnel, they get corrugated or loosened there... i can show you only for P38 but on D3 which is the same like RRS in that area is very similar, you have to pull the console's front bottom side
driver's side on D3
My friends call me Fery
2000 Discovery Td5 ES manual
Hawkeye v.6, Nanocom EVO,
VDM UCANDAS, oscilloscope
if you think my english is peculiar it means you didnt hear my japanese
ALL MY ADVICES ARE BASED ON MY OWN KNOWLEDGE AND MY WAY OF UNDERSTANDING THE DESCRIPTION AND OPERATION OF SYSTEMS... I'M NOT A LAND ROVER TRAINED SPECIALIST JUST AN ADDICTED ENTHUSIAST.