I'm looking for some pics or even a good description of what they look like and where exactly they're located on the axels and T-case

Me too, me too!!!
Wanting to do that for a long tme now, but can't find'em...

My rear D44 had a small plastic(cheap) nipple in it that was just pressed in. I pulled it out, ran a tap through it, and installed a brass fitting. Then I attached a long hose to it and ran it up into my fender. If you don't have any good holes in your axle, you can always drill a new one. Just make sure to pull out the axle and put something in there to catch any shavings. Also, maybe use a vacuum to suck most of the metal out while drilling.

On my front D44, it has a metal tube that's cast into the diff housing.

Generally there is one on each axel, the transfer case, and the transmission. Usually they are on the highest spot available, but my AMC 20 had it at the top of the right axel tube.

Typically they are plastic or steel devices pressed in. They should be replaced with brass or nylon threaded fittings. Packing the hole with grease before tapping it will keep most of the chips out of the case.

I am currently setting up a vent system where all four vents are tied into a common 3/8" tube inside the right frame rail. It will come out at the firewall and run up as high as possible in the engine compartment, maybe into the air cleaner. I might also connect the distributor vent into it.

Mine are as everyone said. I have the little plastic ends that keep crap out. I think 4wd hdwe sells them. My T-5 doesn't have a vent tube. There is some do hickey that looks like a vent. Anyone ever put a tube on a T-5?