SLC rain water plumbing ?
 

Hi,
I have an '81 380 SLC (RHD), ex of Hong Kong, currently in Australia.

I have a rain water leak on the driver's side foot well. Investigation reveals a hole rusted into metal cavity above and to rear of where the various cables pass through the bulkhead.

I further found that an apparent rainwater vent adjacent to the door pillar has been disconected. The short plastic pipe (5/8 OD) passes from inside to somewhere in the door jam.

Does anyone know what should be connected to this, and from where? I'm guessing that the vent which should be connected to this has been blocked off and that this is resulting in water being where it shouldn't, hence my rust hole?

Any ideas?
Thanks,
MarkH