Changed my Distributor cap, rotor arm and ignition cables on my e30 320i.
The Job is not as straight Forward as you would expect! The clearence between the Radiator and the Distributor cap is tight, I found it easier to remove the Radiator completely, two screws on the upper Mounting, undo lower cooler pipe and drain coolant, remove upper cooler pipe and the small pipe that vents to the resevoir. Then remove the Radiator.
The Distributor cap is three bolts and the rotor arm is three allen key screws.
The sparkplug cables are also straight Forward apart from the Signal Sender cable which is attatched to the No6 cable and goes to the plug on the diagnostic plug bracket. I found it easier to remove the diagnostic plug (plastic threaded retaining ring and cap remove) then you can Access the nut that secures the bracket, the plug from the Sender cable is a quick release type where you push the locking mechanism upwards and pull the plug off (The new Sender cable is the MALE and is located on the bracket then the FEMALE plug is clicked on sandwiching the bracket between them).
You could get away with not disassembling the diagnostic plug bracket IF YOU KNOW HOW the plugs GO TOGETHER