Fits all Mercruiser 454 7.4L big block engines with the Thunderbolt Ignition System.
This ignition wire set features 8MM suppression core Packard wire custom fit to your specific application.
You can Identify the Thunderbolt ignition system 2 ways. Number one, the riser has an ignition box mounted to it. Number two, the cap has male terminals coming out of the top and the ignition coil is round with a female plug wire connection.
Works with this style distributor: