There are only three bolts aside from the half shafts and drive shaft that hold the diff in. (not four) Two in the rear and one in the front. I think what Cashburn was referring to was the bushing that the front bolt goes through. Thats a little tough since you have to do it in the car and its about 1 1/4" long. I didn't take the tank out or the sway bar all though I did remove the two C clamps from it and rotated it up. The half shaft Torx bolts are the ones you want to take your time with as they are easily stripped. If you can I would replace them I have part # if you need it, cost about $6.00. If you read this link and cut out all the extras like removing exhaust etc. you will have no problem.
http://www.bimmerdiy.com/diy/e36diffswap