Water leak by kick panels
Dave,
Check the wiper pivot seals. After years, they usually harden and shrink and allow water to enter.
To test, try this: hold an open hose where the wipers attach to the body of the car. Don't wet any other area of the car except this area. I'd wager that this is where the water is entering.
As to how to replace them, you got me. Maybe someone else will chime in. The kit is relatively inexpensive...about $15. You could find it on eBay, YearOne, Laysons, and The Paddock to name a few.
Rob