I dropped the transfer case to do the work. Probably a full day's work for someone comfortable DIY. You have to support the transmission, then remove the rear transmission crossmember. Then unbolt the front and rear guibos. Then unbolt the transfer case from the transmission.

Once it is out of the car, the work is pretty easy. Plan on replacing the chain while you have it apart. I also did all the seals on the transfer case as I didn't want to go back. The rear output seal is hard to get access to (you have to release a big mama-jama nut).

The main output seal of the transmission is also exposed during this process, so I replaced that as it was weeping slightly on me.

There are several versions of the transfer case - look for the metal plate on it (or numbers stamped directly into the case). Don't assume you have one version or the other - some of the parts are the same and some aren't...

Cobra Transmission sells individual parts for the transfer case (all versions) and will answer questions if you call/email them. Not the absolutely cheapest place, but you are getting a lot of expertise for the few extra bucks.

You can order the transmission seals (I have a ZF tranny - don't know what is in a 3.0L) directly from ZF. Write down the exact model and serial number and the distributor will help you look up the parts if you decide to do this.

There are some threads here on transfer case chain replacement and some youtube videos - those show you how to open the case, which is what you need to do to replace the front output spline part. The one part that is not documented is what sealant to use when you reassemble it - it is a gasketless metal to metal seal. I used loctite 518 - it is used by BMW for similar gasketless metal-metal flanges (like R53 Mini Cooper S). Other people have used a ATF-resistant version of RTV.



The question about how to inspect it - the front driveshaft comes out without a lot of work - just unbolt the front guibo and wiggle the driveshaft out (unless you have an aftermarket version with the extended length spline). You can then inspect the male spline on the front driveshaft and the female spline in the front output of the transfer case. Mine were clearly 75% gone.

__________________
David.X5
2001 X5 4.4i Sport
SOLD! at 160k miles