Front differential

[stas23]

I have a 2005 infiniti fx45 and im sick and tired of fixing this car. First of all i changed 4 wheel bearings because the rear one failed on me and the rest of them just started going one by one. By changing wheel bearings i was hoping the noise will go away but it never did. Now my mechanic is saying that my front differential needs to be changed which is a total shocker considering how i cared for the car since i got it.
So, my question is what might cause the front differential to go toast? how common the issue is? How expensive the repair can get? Where would be the best website to buy it from ?
Any help would be very much appreciated.
Just did 3 hours research on google and couldnt find much information on the topic.
Thank you!

[Infinitiguy19]

Differentials don't fail after ~5 years if cared for. Did you change the oil every year or two at least?

Did the mechanic put a mechanics stethoscope to the differential to see if the noise was coming from there?

[BBISHOPPCM]

How many miles? And how often has the diff. fluid been changed? The mileage part is crucial.

[stas23]

Its 110000km and i went to infiniti dealership and they keep telling me its my tires

[Otto.]

Do you have aftermarket wheels on it? That could the the problem, putting stress on the AWD system.

Do you have the same tires all around?

[stas23]

Stock 20inch but my tread might be uneven, thats what dealership told me but i dont think its my tires i still think its the front differential. Does anybody know if there is warranty to replace it?

[Q45tech]

6 years 70,000 miles in US Powertrain Warranty. Canada may be different.