Toyota Repair: 2000 Tundra exhaust manifold, toyota tundra, o2 sensors

Question
I have a 2000 toyota Tundra, 4.7 Liter V-8 54,000 miles, was told that the exhaust manifolds need to be replaced, a $1900 job. I have heard that this is becoming a common problem with the Tundra. What is the cause of this problem? is there a possibility that I  might be able to get Toyota to do anything about this? Who would be best to contact at Toyota regarding this problem?

Answer
Did anyone tell you "WHY" the manifolds have to be replaced, the most common reason is that the O2 sensors fail and have to be replaced and sometimes the sensors will get stuck in the manifold and so the manifold has to be replaced, yes, this is a very common problem. I would contact customer service and explain what is going on.
The O2 sensors are covered under warranty for 3 yrs/ 50,000 miles to my knowledge, I'm not sure about the manifolds without looking at my warranty book.
You may be able to get Toyota to help because this is now a known problem.