Hi guys I'm new to this forum, I have owned my 2003 G35 Aero 5AT sedan for about eight months now, I bought it from a family friend, It has about 190,000 km on it and was dealer maintained most of its life, It had over 4k of work done the past three years, Anyways it had the door bubbles on the pillars which I managed to clean up and cover with chrome pillars, Dealer never told buddy about the 10 year rust warranty Anyway, I live in a place that uses a ton of salt, (Nova Scotia) I found some holes near the rear wheel well between the rocker panel and the floor panel, Those are easily fixed, However my mechanic removed the Rear underbody diffusers and found what they were covering was all rusted out, they said they would have to remove the axles and diff to fix it, and I should perhaps get another car, However I have money into this car and the previous owner replaced the entire exhaust, compression rods, pretty much every bushing and a brand new link kit last year and god knows how much else, I'm trying to figure out what exactly this piece does, Its clearly almost gone and the plastic diffuser trapped salt and slush inside The rest of the cars underbody is in excellent shape, even the undercoating place told me it was excellent underneath for a 2003 Please bear with me, I'm a newbie