65 Dart Wagon Conversion to a Sedan Delivery

I have seen mouse nests inside the pillars make it rust out like on your long roof. Could that be from a mouse nest?

I didn't think of that but it might be. I didn't see anything or feel anything when I poked my fingers in there although if there's a nest, it's likely near the top where the liquid could run down to where it's rotted away - yuck! I'll find out once I get into it depending on which way In go - complete pillar or just the inside panel.