[2002 wonderboy]

sounds like all the front diff fluid is making its way on to the side with the vent tube, and not draining back to the front diff.
I kind of had the same problem, except for it was in my rear diff.
The problem was a casting issue. Where the carrier bearings sit in the housing, there appeared to be a small drain hole(a small groove), to allow gear oil to flow back into the center section from the axle tubes. One of those drains had a bit of excess cast onto it, therefore not allowing fluid to drain back into the center section. I also noticed that this side had a leaky axle seal, probally from all the fluid getting stuck in there and not finding its way back to the center section.
SO, I measured out how the opposite side looked and was machined out to allow the gear oil to drain from the axle tube, and i went at the other side with a cutoff wheel on my dremel and a small file. I mirrored the drain on the other side, and Voila! that side of the axle tube now has a drain to allow gear oil to flow back into the center section.
The front center diff on my 02 is pretty easy to unbolt. 3bolts hold it in, 15mm?and the cv joints have 6 bolts on each flange 12mm 12point. Driveshaft flange have 4 bolts which are the same size as the cv joint flange bolts. once you get the truck jacked up on stands, it took me about 30 minutes to drop the front diff.
Hope this is some helpfull info.