Ok so I put back everything and have not driven it yet.

Here are some things to look out for in this job:

Remember mine is a 2003 3.0 X5 , most likely the last month they put a NV-125 transfer case.

Pulled out case.if you are replacing Chain and the plastic inner pilot bearing then you can probably get away with not even taking the case out as long as front shaft is somewhat loose and not rusted at the splines and back shaft can be half removed by removing bolts near case and center holder of shaft.Car needs to be jacked up high.

You will need special pliers to remove ring blah blah look at youtube video by cobratransmission . I advise taking the case out.

Car needs to be on 4 jacks so all tires can rotate,very important.
You do not need any type of pullers, no need to remove rear triangle thing that is held down by 36 mm bolt, no need for case puller, on the case there is actuality a place where you can put a screw driver to split the case.

No need to remove shift linkage, you can drop transmission down enough to get your hands in there to remove case bolts.observe that you are not putting too much pressure on the cable that runs form transmission to your shifter up there.

the open end ratchet wrench will be the only way to remove case bolts!!!!, must be short in length, previously stated used was 1/2 inch, mine was 3/8 dont know why ? half the bolts you can only feel.So get ready to make love to you case.

For this job get a range of deep sockets 10mm,13mm,15mm many times short ones wont work,

You will probably need 2 people to put exhaust back , and where exhaust is connected to (near sensor) use screwdriver to separate pipes so they fit in, something like that.

By the way transfer case itself is easy to work on, you need at least those special pliers that open that ring. So I looked at mine and guess what no visible signs of anything wrong, no stretched chain, no bad splines, gears and bearing great.

Shoot so what was that noise ???? mechanic verified it was the case.
But I visually verified nothing was wrong, anyways I changed the chain and the plastic bearing, I did not change the big bearing because they lookend new.and was told they almost never go out.besides it looks like big headache to change them.

anyways while down there I found that both front boots were cracked and grease dirty and almost gone,so I will repack those and fix later. Possibly small engine and front transfer case leak.

what joy it is! Don't do this job if you dont have a wide range of tools and you cant jack up the car high enough!