megamacx

The mount is not expensive at all.. However, how much could it be to replace it? Does the transmission needs to be taken down in order to do this?

As far the transfer case goes, the one my car uses is the ATC300 (So I don't think it has a chain.. which I think makes it more difficult to service/repair)

http://www.ecs.steyr.com/typo3temp/pics/88e9f65051.jpg

Transfer case atc 300. Fits: 325xi, 328xi, 330xi, 335xi, 525xi, 528xi, 530xi, 535xi | BMW of South Atlanta

My mechanic said the clunking noise was coming from the transmission internals (not the transfer case).. However I am not 100% sure about that. The video I recorded suggest me to think it is more transfer case related.

turboawd

does your car have any driveline vibration at higher speeds?
if so, i guess worn driveshaft u-joints. otherwise it may be something loose internally in the trans.

megamacx

Nope. It doesn't vibrate at high speeds. What bothers me here is that if this had an automatic transmission, most likely I wouldn't be complaining about it (because even if the problem was there, since being in D (Drive) makes the car push forward all the time, it would have kept all the transmission/transfer case components tight at all times). However, since it is a manual transmission, I do feel/hear the noise every single time I use the car and shift gears. At the end, I love manual transmission, and therefore I want to get rid of the issue.