Transmission growl

[realbrotha31]

I was wondering if anyone has had problems with there 2000 Navigator transmission. Once I make it to 45 mph the truck growls and then it goes into overdrive. There is a small leak at the rear axle where the drive shaft meets the rear axle. There is also a mega amount of rust that comes from under my truck when it rains or moisture is out. Lincoln has a 70,000 mile rust warranty is true.

[pro-five-oh]

Is the rust coming from under the battery? Check there...maybe your battery leaked acid.

Not sure about the transmission thing, its not a common problem from what I have heard. What does the fluid look like? Red or black? Maybe its time for a flush, a new filter, and lubeguard added to it.