Some of you have heard from our e-mail lists people talking about 6-volt and 12-volt flywheels. This is not a misspelling; it's a reality. The trucks older than 1955 that have 6-volt systems require a 139-tooth ring gear of 4 teeth per inch, while the 12-volt systems that are generally associated with the newer-style 235 engine have 168 teeth, or 5 teeth per inch. When installing a new-style 235 or 261 engine in your truck, and you desire to keep the 6-volt starter, you want to make sure you keep your 216 flywheel. If you try to mate a 6-volt starter with a 12-volt ring gear, the starter drive will grind and fail to engage. The old 6-volt starter with the floor "kick switch" will work perfectly fine on a 12-volt system so this enables you to keep your starter system original.