water leaks

put a heater core in it

you could check your windshield wiper pivots , they each have a gasket with 2 or three bolts

check the winshield waper dip...thats the dip under the wiper arms,, its got a drain hole in it,, the tube could be pluged ot it could be rotted off at the boddom if its the heater core youll have a wet spot under the heater pod drivers side neer the fire wall.

also the wiper pivets dont even enter the car so thats not it,,,

Hard to tell unless you get underneath the dash and find where it's leaking from it could be a wiper/seal like stated above or rust due to it being a bit old. Good luck, a good sealant is your friend in this case.

definitly the haeter core or the hose going to it, an easy fix