Hey, welcome to the Altima community!
I haven't seen those gauges with a moisture issue before but it definitely sounds like there's something not right with them. It could be something as simple as they were banged into or during a headunit install/removal they were damaged, breaking the seals that keeps moisture out of them. Are they still working properly? I'd think that's the most important part.
As for the vibrating/rattling, you'd have to get under the car and check, there aren't too many heat shields in the rear of the car (not on mine at least). It's tough to say where it's coming from without actually being there to hear it. Even though there's a paper plate, is there a license plate frame around it? it could be that if so.
__________________
2006 Altima SER - NWP BOP & Spacers | CAI | RL FSTB | Dimple & Slotted Rotors | Redline Tuning QuickLIFT | Plasti Dip Wheels & Front Bumper | CarTab Project
|