fs-rodeo

Just had this happen to a buddy of mine the other night. Rear wheels locked right up, no metal in the fluid, took the case off both sides and it was clean, gears and such look good. The case was way low on oil. The only thing I can figure is it is in the HIGH-LOW-SUPER LOW gear set. The center gear at the inside of the case, held in by a c-clip, is seized to the shaft, as far as I can tell it should spin. It is also not lined up with the dog on the splines. Has anyone hear of this happening?