I installed my 123 Ignition distributor on my 1981 911 SC with 6-pin CDI box without difficulty. The car hadn't been running well for a while, with an intermittent fast idle when hot, down on power, etc. After rebuilding my alternator for a noisy bearing, I could suddenly hear another rotary noise that turned out to be worn out distributor bushings. So worn out, that the inductive pickup points could touch! I elected to go with the 123 distributor and rebuild my original as a spare. After lots of thinking and planning, it ended up taking about 90 minutes total to install the ignition and time the engine, including fabricating a nice looking wiring 'harness' from expandable wire cover. I decided to put a 4-pin connector in the middle of the wires to facilitate future removal, and made all connections at the plug to the CDI box. The original "Green Wire" that carried the signal from the old inductive distributor pickups to the CDI was removed from the CDI box plug, and the green and borwn wires had terminals crimped on and inserted in the appropriate places in the plug (BTW, the old 'Green wire" is a Coaxial cable, selected to protect the signal against electromagnetic noise from the various spark plug wires and other electrical components in the engine bay. It would be great if the distributor used a similar wire for the same reasons, but maybe it's not necessary because the electronically generated signal can be so much bigger than the inductively generated signal in the old distributor? ) Anyway - Red (switched +12V and Blue Chassis ground) were connected in similar fashion to the CDI box plug. Everything was reconnected. After checking that the engine was a TDC for cylinder 1, I inserted the distributor into the engine case after aligning the rotor with the position of one of the plug wire sockets on the cap. I marked the position with a Sharpie for easy alignment (Tip: put a little assembly lube or engine oil on the distributor drive gear to make it easier to insert). It was a surprise that the hold-down bracket is fully adjustable, but it also makes it a lot easier to position the distributor so that wires and vacuum port are conveniently aligned. I didn't tighten the hold down onto the distributor case until I'd completed the "Rotate CW until the light comes on, the rotate CCW until it turns off" routine. I then held the distributor in position while rotating the hold-down bracket to be centered on the stud, and tightened it down. Reconnected all wires as instructed... Connected plug wires in the appropriate CCW order from #1. Plugged the vacuum lines with a couple of golf tees, turned on ignition to allow connection to the app, and started the car. It caught immediately, and I then went through the process of checking the base timing and idle speed. (Instructions are printed right on the sticker under the hood! and detailed in multiple other sources). The engine is idling beautifully, advance comes on as expected, and the entire car sounds and drives much better than it ever has during the 13 years that I've owned it. New plugs and wires are next. I highly recommend this distributor system! Fingers crossed that it'll last as well as the last one did!