Yes definitely a trapped condensation issue. It seemed to go hand in hand with a rotted out floor or very wet underlayment. Which is a result of cowl cracks, another Dodge faux pas.

I thought long and hard as to the cause and this makes the most sense.There is a constant source of moisture inside which when heated rises and condenses at the high point. I used to think it started on the outside, but it is definitely inside out.

I wondered why I had seen it on trucks from dry states( ocassionally) and yet trucks here in the snow/ salt belt would be hit or miss. I noticed that trucks prior to 1986ish didn't have it quite as commonly as the later 80 and 90's models. One thing I noticed was the older trucks didn't have as much fancy interior cladding to absorb and hold /trap moisture. I also wonder still if the cowl crack problem was as prevalent then or if the metal/processes got cheaper and cowls cracked more.

When thinking it was from the outside I thought it was found more in trucks that drove highway speeds than local (i.e Municipal Gov't trucks). I thought plowing drift that was salt laden riding over the front was causing it.Yet, I wned trucks that had been always highway driven or always plowed with that appeared fine.There was no common thread.

It was here that someone suggested the interior moisture dilemma. Now it all makes sense. I despise rust so I had to post up and get it off my chest in hopes of helping. Please do as they say and get some lube up in that area even if nothing is outwardly visible as even a pristine truck can suffer this. And fix the cowl cracks and other water intrusions as they add up and contribute.Sorry for the long rambling...ahh I feel a little relieved.