[myfirstcar66]

Some of the holes in the kick panel sheet metal are supposed to have rubber plugs in them. One on the passenger side is a grommet type for the radio antenna wire pass-through. Even water that doesn't leak through the cowl, doesn't leak through the windshield, or doesn't go through a rubber plug hole may still get by a welded, braized or seam sealer treated joint that is just a natural junction of a lot of pieces of metal in those under-dash corners. You'll probably need to remove the front fenders to eliminate it entirely.

 

[myfirstcar66]

These things should have been galvanized in 1964 and later, and the reproduction pieces DAMN sure should be, knowing what kind of problem they are prone to. I would gladly pay extra for a part I know I would most likely never have to replace again.

 

[myfirstcar66]

Oh, my goodness. There were about to be multiple melt-downs over a car wash !!
I can see where a true touch-free car wash may be okay but I can just see the antenna or something getting ripped off a car at the Goo Goo.
When I lived at an apartment complex, I had a connector on my kitchen sink and a 100-foot hose to wash my car in the parking lot.
I'm guilty of taking a wash bucket, soap and mitt with me on vacation ( or buying if I forgot it) to get bugs and road grime off my car when I get where I'm going.
That said, these cars were prone to leaks when new, let alone after 50 something years. I will occasionally spray too hard at the sides of mine and get a little bit to come in around the side or vent windows. Oops. I'm not sure they can be made to be 100% leak-free. That's part of why they rust so easily.
I would recommend as others have to become or find a contortionist to lay under the dash and look for the source of the leak with bright lights or water, and make sure the windshield is sealed with a tube and a half of 3M B&G C. Otherwise, the leak may be coming from a place where seam sealer has lifted off. I fixed that in an otherwise perfectly solid cowl by using a 360° spray wand to spray sealer on every surface and pouring some in through the taped-up cowl air intake to the point it spread over the entire cowl floor and actually ran out the side drains behind the fenders. No more leaks. Good luck!!