The front differential on my 99 Ranger XLT 4x4 developed a crack and lost all fluid. Smelled burning oil in 2WD on highway and discovered the leak, which was large and must have just happened. There was no disturbing sound or clunk. Thought i may have picked up a rock or something but it looks to be from within (see pics below). I checked the manual hubs - one was locked, one was not, so the axle was turning. Unlocked the hub and continued on my way with no problems (other than gear oil all over underside).
I have since tested the diff by manually turning the axles and also the 4wd crankshaft and everything seems to turn/work without any weird noises or action. Engaged 4x4Hi and drove forward and back a few feet with same positive results and it disengaged properly when switched back to 2WD.
Only recent thing i can think caused this is we mildly 4 wheeled it just a week ago and it did have a prob getting back into 2WD from 4WD low but finally got it back over.
Any insights as to possible cause/internal damage? If there is no problem in there, would it be possible to get this welded as a first step rather than replace it or is that the only option to get 4WD working again?