It's not too bad, more a pain in the butt, 'cause you have to get all kind of stuff out of the way so you can get to the darn thing. There are six allen bolts holding it on. Be sure to clean them out, so that your tool goes in all the way, and you don't round it out. A 3/8 socket won't work because the head is too fat ( the part that the ratchet goes in to), so you'll need to get some long allen wrenches.
From what I remember, you have to take off the main vacuum line, loosen the p/s belt, the a/c belt, take off the top of the fan shroud, and the fan itself. This ought to give you an idea as to how long it'll take you. Good luck, and don't be in a hurry.
03/83 300D 184k
07/73 280 160k