What you should be buying would be the crankshaft position sensor.
Great that you've got the pump. ;-) You'll need the fuel pump's fuel tank entry orifice's O ring as well. If you forgot that, please purchase it before installation.
Please don't forget an assorted set of car fuses kept as handy spares, and new relays for your fuel pump, dme, abs and o2 sensors. Especially a new relay for the fuel pump (but you might as well get them for everything else along the way). The old relays can be kept as spares.
You're nearly at the point where you'll be sitting back, reading posts, and wondering why people have no start problems with their E34s.