Add this to your "Water Leaks" file.
 

Every time I washed my 74 911 there is an inch of water on the passenger side floor. After much poking around, I identify huge leak at the front due to the missing hose which is supposed to drain water from the heat/air mixing box. Fine, says I, I'll just order one. Problem solved.

My local guy can't get the hose. Vertex has on back order. Pelican is out of stock. Performance says it is unavailable. Paragon doesn't recognize part number.

Off to neighborhood hardware stove. Find plastic hose with perfect 7/8" i.d.
It's too stiff and too big and I can't make it work. Go back for lighter hose. It's too small but maybe with heat I can make it big enough. Wrong.

Vertex emails me to say they don't know if they'll ever see one of these hoses again but if they do I'll be the first to know!

Rummage thru old parts box. Find bike inner tube. Cut section to fit. Fits perfectly, just a bit snug. I add a hose clamp just to be sure. I wash car. The 1" of water I've grown accustomed to on the floor is gone!

It's a miracle.

Can you post pics of fix - I have the same problem :)