the crank... hard to explain if you have no idea...
you need to be worried about the big pulley at the bottom of the engine, all of the belts go to it. only turn it clockwise. you can get a breaker bar and a big socket (forgot the size) and manually turn it. there will be several little notches in it. they can be hard to see if there is gunk on the pulley. so look carefully. there is also a little pin that sticks out of the block just about the pully. a little to the driver's side. line that pin up with the second to last notch. (i used a white out pin to make the notches more visible) thats top dead center. when you put the Dizzy in, you'll have to turn the rotor (the thing that picture is pointing at, that you're old dizzy didn't have) too far, cuz when you put it in, it will turn itself back. if you did it right, the rotor should be pointing towards the #1 spark plug wire... If everything doesn't line up right, don't try to start the car. It has to basically be perfect or it won't work.... you'll have to fine turn the dizzy once you get it lined up right, but for now, worry about getting it in right.
and for furture reference, when that little white piece isn't there, all you have to do is replace that little piece, you don't have to replace the whole dizzy. so next time, you'll save alot of hassle. hit me up with a pm if you need more details. I've done this so many times I can basically do it with my eyes closed...