Here’s what you can expect to find. On the left is a ’69-’70 style compact horn with the long core support bracket. At the center is a ’65 through early ’66 compact horn with a dimple reference mark for proper installation. On the right is a ’66-’68 horn that has a bracket with a reference tab instead of the dimple. Regardless of bracket type, these horns are all the same. The only real difference is the high versus low pitch housings, which are different castings.