For a flywheel you will have to find a 55 2nd or later flywheel drilled for whatever clutch you want to use. 6V and 12V starter drives are not interchangeable so you have to use the 12 V starter with 12 V starter drive. Flywheel ring gears are not interchangeable either. You have to have a 12V flywheel as the 12V ring gear does not fit the 6V flywheel. Don't ask how I know, it was a long process. Some 6V flywheels are drilled for 9 rather than 6 clutch bolts to accommodate the larger clutches, which are 10-3/4" rather than 11." 9 bolt clutch covers are no longer available so you'd have to have one rebuilt. I have run a 6V starter on 12V for 20 or so years with no trouble. It does spin the engine over faster and sounds different. It is presently starting a 9:1 CR 261 without complaint even at 0 deg. F.
