It wasn't too bad. The hall sensor is inside the distributor and does tells the ECU where the crank is so it knows when to fire the spark plugs. I needed to buy a new distributor because the later dizzys (my van is a 1990) need a hydraulic press to get them apart and get the hall sensor out. It was a case of setting the engine to 5° before TDC on cylinder 1 (turn the engine so the rotor points to cylinder 1 and V notch [not the U notch] in the pulley is in line with the case join), removing the distributor, putting in the new one, static timing it with a timing strobe (put the timing strobe pick-up over the plug with to Cyl 1 and, with the engine on, turn the dizzy until the strobe flashes), then once it was running setting the timing properly. I set the timing dynamically rather that by the VW manual because it is much easier and gives the same result The video shows the notches on the pulley I am talking about. Don't worry about them saying the timing needs to be done at 3000RPM, the engine needs to be doing 3000RPM or more. That is the RPM that the maximum timing advance is reached. If you rev the engine higher and the timing advance doesn't change then you are at the right RPM. I made it harder for myself by thinking that because the Hall sensor was 180° different from the original dizzy that I had to move the spark plug wires too, but that was wrong, everything goes back together the same way.