02 Z71 front Differential and Transfer case

Here's my story, I have asked around and can't seem to find an answer. I purchased my 02 Avy in Dec 2014. She is an amazing machine. About 2-3 months ago my rear differential went out and had to have it the entire axle replaced. Last week it started making this nasty rattling type noise near the front end area(about 4 months ago I had the front end redone i.e. pitman arm. idler arm, upper & lower ball joints, inner & outer tie rods.) I took her to the shop who did my rear end work which happens to be the best shop in town and the guy drove her and said it sounds like front differential bearings or the transfer case is trying to switch gears which my transfer case hasn't worked in a couple months. I replaced the 4WD switch and the transfer case motor and nothing. So I'm stuck, if I have to have the front differential replaced or transfer case replaced or both, what is my best way to go about it? Some have suggested trying transfer case first and others say both need replaced. My Avy has just over 186k miles. Any and all help would be greatly appreciated! Thanks 

SECOND opinion from another mechanic.

I'm guessing your mechanic did not think of replacing the Transfer Case Control Module.

But really you have a 13 year old truck things are going to wear out, you can't take it to a mom and pop shop who drive it to diagnose what is wrong. Find a good mechanic who has the tools to do it right.

My front diff was pretty worn when I bought my truck at 116,000 miles.

I had it rebuilt at around 150,000 miles.

It is quiet as a church mouse now.

I never had any rattling.

Probably the biggest noise would be described as a loud whine.

My transfer case could probably also use a rebuild, but it is not nearly as noisy as the front diff had been.

My transfer case and front diff are somewhat different than yours in that with my all wheel drive they are both constantly engaged and can not be turned off.

As I understand it, your front diff has additional parts that allow the front diff to disengage when in two wheel drive mode.

That means you could also have additional parts that may be worn out and cause some of the noises you are hearing.

If it were my truck, I would have both the transfer case and the front diff checked out and fix properly.

Good things are not going to happen if you just let them both rock on.

The first gen Avs have an issue with the transfer case. You are at about the right mileage. There is a motor inside the transfer case that grinds a hole through the casing leaking out all your fluids. I found this out the hard way also. Good news is there is a kit the fixes this issue without having to replace the transfer case. I think mine cost about $150.00 total. Have that checked at a reputable shop. I have 219k on my 02 and have had to have my resend replaced twice. My front hubs 215k still were in good enough shape to not need replacing. And I am the kind of person who believes if you remove it replace it. My mechanic convinced me it would be a waste of money and reinstalled my OE ones. I have a very trustworthy shop, which took me almost 10 tries to find. Luckily I know enough about mechanics to know when I am being bullshitted to. I would purposely create a simple problem to test if I am being lied to. I once put in a blown fuse to my left headlight. They had the truck 2 hours and came back with a list of stuff wrong with my Av. From serpentine belt to shocks, joints, brake Padres warped rotors, exhaust leak, bad alternator. I politely said thank you and drove away. What they did not know was I was a volunteer Sheriff and this shop was our repair shop for our vehicles. When I brought this up to my supervisor they went and found a new shop.   

Basically all I am saying is be careful. These trucks are very durable, I know I have pushed mine way beyond her limits and she is still going. If you go to a shop and are unsure come here and ask. I am sure someone has had the same issue.