The Pertronix module drops into the distributor you have, unless you are asking about a Pertronix distributor. Frankly, since I have put many, many distributors in the machine, I'd be really sceptical about any sellers' claims of "ready to run". I have never seen a distributor that had an advance curve that was within Ford specifications (before being adjusted), and lemme tell you, it makes a difference. Even if you don't change the total advance, the curve leading to it can be the difference between a dog and a tire-shredder.
