Appears that concentric slave cylinder is leaking somewhere but I just can't actually see source of leak. Cylinder looks pretty simple design. Could body have cracked causing slow leak or just a fitting seal bad on bleeder screw or inlet tube.
All of a sudden had shifting issues one day. Hadn't actually checked fluid level in quite a while so no surprise it was low. Fluid left was very dirty/dark so I bleed system until all new fluid throughout system-thought problem solved. Shifting issues returned and fluid was again low. Investigated further and did find slow fluid leak while sitting. Very small leak on ground under trans/engine joint. Fluid leaking somewhere inside trans housing then running down trans housing until it drips out. Can't definitively see drops coming from either inlet connection or bleed screw connection. Truck drives/shifts GREAT as long as I top off master cylinder before each trip. Commute 43 miles one way and still full upon arrival. Sitting at work for 8.5 hour shift and at home between shifts fluid slowly leaks out. Never enough that it needs to be bled, just topped off again for every commute. Have been running a couple of weeks this way not wanting to replace whole clutch assembly which works great but tired of adding fluid 2X daily.