It is important to extend the many vital breathers higher than they come from the factory to stop water from entering the components while doing water crossings. The things covered here like the diffs and transmission etc, cannot be sealed as the oil heats up it expands along with the air pressure so must vent to prevent blowing seals. The problem is when crossing rivers is that these components will cool with the water against them and therefore shrink in volume and draw air in just when you need it the least. Raising them to the top of the firewall will prevent all this from happening.
You will need nylon ties and a selection of tee pieces if only using a couple of fuel filters for them all or none at all if having a filter for each component if you have the room and the budget for them. I have done all the vents using 5 meters of 1/4" hose or I buy around 3 meters of 1/4" nylon reinforced hose for the rear diff and 2 meters of 5/16" to extend all the other vents which are a bit bigger stock to start with. You will need joiners for each component as well. I always extend any existing vent hose rather than trying to get the old off and start from there as the stock rubber hose is more flexible too. You can even vent the distributor cap like shown pushing out the little cap that sits in there normally and finding some rubber hose to jam into the hole and then attaching the nylon hose to that or some bigger hose to go over it and run it to the filter. To pop the old vent cap you simply squeeze in the two tabs that hold it in place from the underside of the cap.
You can just pull the rear diff vent off the frame where it enters into it. You can even pull the fitting out it attached to and pull it apart to use as a joiner. Now I found it is very important not to let the hose run up and then back down again as the rear diff can sometime pump oil up into the vent, ( see here how to stop most of that from happening ) which then pools at the bottom of the dip blocking the hose. So make sure you have it sloping up like shown and then attach it to the fuel lines with zip ties.
Shown above is a gearbox vent on a TJ I did. I just forced off the metal cap with a large screwdriver and then used 10 mm hose that I bored the end of it. I did this by putting a hose clamp around the end of it will screwing by hand a 1/2" drill bit into the end of the hose. Then placed it in some boiling water before pushing the hose over the vent and securing it with a hose clamp.
Other vents I extend are the transfercase and automatic transmission. Just follow the existing hoses where they go to with one ending near the bottom of the firewall amongst the wiring loom that comes up past the auto dip stick and the other terminates at a open pipe at the top most bolt of the bell housing. This one is just yank off the metal pipe fitting it attaches to as too hard to get up there to remove it. I top the vent hoses of with either Ryco Z91 fuel filters or Repco RFF 9192 universal ones which have both a 1/4" and 5/16" ends on them. These will keep the dust out of the components will will help extend there life and keep the oil cleaner. Any fuel filter will do but I like the ones with a elbow on them as a bit more protection from any water dropping straight down into the ends. Most times I have done this I have put the auto, transfercase and distributor together with one filter using tee pieces that you can just see above and then the two diffs together on the other side of the engine in another.
With mine I have a filter for each thing which are from left to right: Automatic Transmission, Distributor Cap, Transfercase, Rear differential and Front differential. On RHD's we have a convenient vacuum hose which goes across to the brake booster to attach them too. You can either attach them with a zip tie over the end like the second last shot or by using two zip ties with one around the hose and the other looping through this and around the body of the filter.