the differential in my 04 is making a whinning noise as the vehicle slows it has been replaced a while back also (by DOdge) is the rear end the weak link in the power train and can i replace it for one that will speed up my truck

 

Are you still under warranty?? If you are take it back.

 

I'd second that

 

if you are not under warranty than answer me this... 2wd or 4wd and is it lsd?

 

Some people have problems with the Chrysler rear ends, but for the most part, people don't. Iplay golf witha service manager at a RV dealership who used to be one at a Forddealer and then my local Dodge/Jeep dealer (that's where I got to know him).
According to him, YES, they have more problems with the Chrysler rear ends (made by AAM) on both the 1500 & 2500 trucks than they did when Chrysler used Dana's, but that he saw a lot more rear end problems when he was at Ford.
You want more get up & go out of your differential then put in a set of 4.56 gears. Night & day difference...

 

its a 2 wheel drive and the dealer said it comes equipped with mopar 3.92 diff I dont know if thats a LSD will the 4.56 make a difference

 

I have a 03 2 wheel drive. It has the 3.92 gears and it is a limited slip diff. I'm sure the 04 is probably the same.I have every intention of replacing the diff and putting taller gears in. It's on my list of things todo. I've got a pile of parts to put on first.I've been accumulating them while I'm deployed.

 

Typically, how much does something like that go for? And would you have the dealership handle it or someone else?

 

It depends on what brand you buy. I've read in a few threads that the Auburn seems pretty good. But your probably looking at a starting price of $400.00. I personnaly I don't trust dealerships.When I have a job that I can't do Itake my truck toa place that I've done a lot of business with, and I have themdo it for me. I'm not sure when I'll get mine done. I have to get out of the sandbox first.
I've seen an Auburn limited slip at www.airram.com for 384.00. They list an install price in Texas as 335.00. If you do it you might as well get the master bearing kit too. Since it all has to come apart anyway.

 

Thanks for the info. Keep your head down, and remember it's better to be tried by twelve, than carried by six.