I've got this problem that's been driving me bananas for some time now:
My girlfriend has a 1985 Ram 50 that collects water on the floor when it rains (and this is SEATTLE!). I've replaced the window "squeegee" seals in both doors with new units, to no avail. She says it only collects water when it's parked facing uphill. Problem is, the truck has a very nice bedliner and the BED fills with water if it's facing downhill!
I can't seem to detect any leaks or trickle stains anywhere, but there's no denying the big puddles on the floor.
This is a very nice vehicle otherwise, and it would be a terrible shame to let the floor rust out because of this issue.