Ry.con

So I have a 1994 toyota pickup v6 manual, 1 and a half cab, chain driven transfer case. It's looks just like the tacomas but before they were called a tacoma. Last winter a random rumble or whirring sound started to randomly happen and could be stopped by a big bump, it stopped almost all summer. At this time I had 30x9.5 tires on front and 31x10 tires in the back. I was told this could cause problems within the transfer case. This winter the noise started happening as soon as I went above 5mph. I was able to stop the noise by putting it into 4wd but now the noise even happens when I'm in 4wd or 2wd. It seems to be coming from the front to mid passenger side, under the truck. The transmission looks like it is leaking, the transfer case has a faint noise and a little play when I turn the front driveline, however the front differential also seems to have some moisture coming from the spot the front driveline connects to the front differential. I took out the front driveline to see if there was a difference but there wasn't. The sound best reminds me of destroyed bearings or stripped gears. My question is where and what could be causing this noise. I prefer to do all my own work and am trying to avoid taking apart everything one at a time till I find a big problem. Any ideas of what this could be? I already know its not the wheel bearings or cv axles. I have narrowed it down to most likely being something in the front differential or the transfer case and recently read something to make me think it could also be in the transmission. Any ideas?