It is a little while since I have worked on one of these but as far as I can remember the head end 'diff' is held onto the drive shaft outer tubing by one or two pinchbolts. All you should need to do is slacken or remove the bolts and the diff should slide off. Carefully easing apart the gap the bolts pinch up may ease removal but be carefull so as not to split the housing.
Robin S
August 2008