Differential Unit problems of the 2001 Toyota Tundra

The Toyota safety recall work done in 2012 to treated my vehicles frame to prevent rust perforation has failed. During nh state inspection areas where the frame had rusted through were identified. These areas had been treated under Toyota's guidance and at their expense. Due to frame rust perforation, and rust issues identified below my vehicle would not pass inspection. Toyota of portsmouth, where the initial recall work was initiated, and Toyota motor sales have both denied to remedy this situation. Many other 2001 Toyota Tundra owners were provided complete frame replacements. I was provided with a rust treatment that has failed to correct this safety issue. The state inspection was requested by me prior to spending $2,776 (and up to $5,000 or more if internal parts were damaged) to replace a rusted through and leaking rear differential case that could have seized up at highway speeds if I had not noticed the leak. This inspection also identified for the second time a rusted through and leaking exhaust manifolds (the left manifold was "starting" to leak on 09/16/2014 when the truck last passed inspection. I heard the ticking sound, characteristic of this leak, since the vehicle was under warranty and told it was normal. The body and bed of my truck was determined by a local body shop to be in good condition with minimal rust. This was determined by visual inspection and the condition of the lower portions of the doors which are frequently a trouble spot in states where road salt is used and the first locations where rust (body rot) appears. Toyota has failed to provide adequate corrosion protection on the frame and rear differential of my truck and created serious safety issues. The frame rust treatment Toyota used on my truck did not work. I do not understand why they have declined to remedy this situation. They have replaced many frames for others.

While driving my 2001 Toyota Tundra a leak developed from the rear differential spraying gear oil onto the road and vehicle behind me . I had my vehicle towed to my mechanic for repair . I believed that it would probably be a 2 yo 3 hundred dollar repair for a seal or gasket but was informed that the rear housing cover had rusted thru and that because of the design the only way to repair it is to replace the entire rear axle housing at a cost of a little over $ 2,000 . The vehicle is in very good condition and there is not even rust on any of the fenders . I contacted the Toyota customer experience hotline and explained the problem to both the first person I spoke with and then the follow up with a case manager . They informed me that there was nothing they can do and the only rust issues they would deal with are with the rear frame . My experience with older vehicles that had completely rusted bodies and frames never had differentials rust thru . I am being forced to get rid of a vehicle that I purchased new in 2001 due to a poorly designed part . Not only is this a design flaw with an unservicable part but also a safety issue with fluid spewing from the rear end onto the roadway and vehicles traveling from behind. Also after researching this problem on the internet I discovered that it is a widespread problem with the first generation Tundras that Toyota refuses to address .