heres my 2 cents on waterproofing on the cheap and i'm living proof that it works.
Snorkle: PVC out the fender upto the roof with a sewer hat ontop. if not a sewer hat, a peice of window screen wire tied onto an angle facing away from where mud will shoot into it. Keep snorkle as large as a idiameter as you can and as straight as you can, to small of a diameter and too many bends will be too restrictive and bog out your motor. use stock filter and housing. altogether TOPS $50
Vent lines: Everything lubricated with moving parts within has a vent, from the factory they only have little hats on the top which dont do well at all. rip hats off of nipple and get fuel line to slide over nipple using a hose clamp to clamp on and run as high as possible. axle housings, transmissions, transfer cases and all. also dont forget is you see oil leaking out anywheres, water can get in. Also dont get to fancy with running your vents. if you run them all to one common line it will not allow the pressure and vapors to vent causing seals to blow out. Do not run fuel filters on top of the lines for the same reason. Do not have any sharp angles for the fact that the oil residue will collect dust over time and cause a blockage also causing the same results as above.
Seals: all must be in tip top shape, water and sand will find their way in if oil can find its way out. when reinstalling hubs or anything else that is metal to metal, be sure a new gasket or o-ring is used, if there are any surfaces that have neither be sure to use RTV silicone.
Computer: if you have one, and this option will fit, do it. get a rubbermaid (or something similar) container as close to the size of the computer as you can, remove the computer from the vehicle and study the plugs, cut out the container to where the plug will just fit. poke holes on bottom of container in same location as mounting hole for the computer. mount container and computer in location, using silicone at the screw holes. put lid of container on generously using RTV silicone. get some di-eletric grease and smear some on the plug, replug. use generous bead of silicone around plug area of container as well.
Ignition: remove sparkplug wires and smear some Di-eletric grease on the porcelin body of the spark plug. get more D-grease and spread at point where spark plug boot joins the wire. re install wire. closely examine distributor, any holes on the bottom of it, make sure they are sealed off with silicone, take of dist. cap re-install with a bead of silicone on mating surface where the cap meets the distributor. remove wires and spread D-grease the same as you did with the plug, be sure to do same on coil. If you cap has a vent on it, break off the cap and install a peice of fuel line going as high as you can. (Some people will say not to completely seal off your distributor , I have done it, and NEVER had a problem. seal all eletrical connections off with d-grease as well.
Dipsticks: get old aprk plug boots and put it around the finger handle of the dipstick and when you put your dipstick back into the tube spray a little WD-$) on the tube and slide plug boot over the tube.
Fuses and relays: Remove one at a time reinstalling with dieletric grease.
Splash gaurd: If you are not to concerned with looks (obviously you are not if you listen to my PVC idea. hang a mud flap or floor mat off of your front bumper and let it hang about 3" off of the ground, when you splash threw a puddle, the force of the water pushes the flap up and redirects the water away from your motor.
Wheel bearings/ rod ends/ and ujoints: GREASE, GREASE AND MORE GREASE. Check these every week, it only takes a few minutes to hit every grease fitting on a vehicle. Keep the wheel beearings packed with fresh grease. If you are confident with your skills enough, drill and tab into the wheel hub in the bearing area, 2 holes one on bottom one on top. tap top and bottom holes to take inverted allen plugs. when you get home or are going over your truck for a quick greasing, remove both plugs, leaving the bottom hole open, insert a grease fitting, the same thread as your plug into the top hole, get your grease gun and go to town catching the dirty grease out of the bottom. this is by no means as efficent as cleaning and repacking your bearings, but it will help prolong life and keep water off of them.
Hopes this helps some of you, all of this can be done in a weekend on a very low budget as well and will definatley save you time and money in the long run, and keep a smile on your face as people watch you submarine your vehicle and come out the other side not sputtering, or if you just want to wash them mud clumps off your truck at the end of the day by blasting a puddle at 30MPH (realize that is speeding in the state forest, so dont do it there and make sure there are no foreign objects in the pudle you decide to do this in) If you are not up for doing this just contact me and I'll help ya out or even do it for you.
Also I take kindly to constructive criticism and comments ;D
oh and my jeep sat stuck like this for about 10 mins and didnt miss a beat. ;D