The stock breather for the transmission and transfer case is mounted fairly low.  Since the transmission shares oil with the transfer case, both use the same breather.  If you drive in water up to the floorboards, it is over the top of the breather.  In the event of a flooded Dairy Queen parking lot, I relocated the breather somewhat higher.  As a big plus, it makes an incredibly handy spot for topping off the gear lube.

Here is a passenger side shot of a transfer case sitting on my workbench.  The stock breather is a piece of pipe with internal baffles and a cap loosely held on with a cotter pin.  By unscrewing the breather, a threaded elbow can be inserted in its place:

Here is a front view of the transfer case installed.  Since the breather is directly behind the shift levers, two elbows were used.  The first elbow, pointing to the side, threaded directly into the top of the transfer case.  The second elbow was threaded into the first with a hose barb pointing forward.  This let the line point straight forward and clear the shift levers:

Here is the breather fitting on the firewall.  The clamps are secured to the air cleaner brackets so no extra holes were needed.  You could mount the breather anywhere you'd like, but watch out for rainwater which runs down the firewall.  This is a homemade breather fitting, but industrial suppliers carry similar fittings for exhaust on compressed air systems:

Here is the best part, topping off the gear lube.  The breather cover unscrews and the gear lube bottle fits in the line.  For monitoring, click here to see the oil level gauge on the back of the PTO drive/Transfer Case:

 

When it comes time to drain the fluid, that can be a chore.  The transfer case drain is easy to reach, a plug on the bottom of the pan.  But the transmission drain will dump fluid all over the crossmember.  Here is a view from the front, showing how I added a pair of elbows to let the fluid clear the crossmember when being drained.  The elbows are well protected above the skidplate which is not shown.  An appropriate hole in the skidplate allows reaching up with a 3/8" drive socket extension to unscrew the plug, just like at the transfer case.  Note the bolts and nutclips used to secure the skidplate.  This makes removing the skidplate far easier than reaching the original nuts above the crossmember.  The camera angle is a bit confusing, but the bolt is not in the way of the drain:

Here is a view from the driver's side.  This lets you see how the oil will drain forward of the crossmember instead of all over it: