Thanks for the update, both fluids looked like they had water in them the right hand one for sure. Since your describe fairly normal trail riding did you check the vent lines from the front and rear diff to make sure one or both hadn't come off or torn? I realize you changed the fuids a year ago. Normal color for the used diff fluid is dark almost black, lightly used may still appear dark green?
Your note on the Ford friction modifier is interesting since the visco lok front end dosen't have any sliding clutches per se and the visco part is sealed with its own high viscosity fluid which activates the movement to apply more force left or right. The friction modifier was used in pickup rear (Ford, GMC and Dodge) ends when they chattered going around a corner for example.
Good to hear everything sounds normal a year later.