Carpet replacement

Hey

Ive got an 88 350 regular cab c1500 and I'm replacing the carpet that was damaged from some water leak. I changed the heater core about 2 months ago to stop the leak and aparently it has stopped, but when I took out the carpet today, it was soaking wet underneath the jute padding. Is this normal, or is there any other place that it can be leaking from. The paint is pretty rusted, and I guess its an indication that the water has been there a while, so I'm guessing all of the leaked water from before just stayed there, but I'm not sure. Now, I'm riding on metal and haven't seen a drop, but I want to make sure no other place can leak before I put the new carpet in. I know about the leak tube for the air conditioner, but water comes out of it from the end of the tube outside the car so I'm assuming its OK. Another question is, what kind of material can I use to clean the rust up on metal that got messed up from the water or is there a good spray I can put down before I lay the carpet, and what are the general layers of carpet that I need to put in my car, i.e. insulation, sound padding, adhesive, etc. ect.

Thanks,
Matthew

check the seals around the windshield