i have a chrysler 55hp that has been completely rebuilt except for the main drive gear ( believe it is called the pinion gear?) model #559ha serial #4140. i was told that the only way i could get that gear was to buy a new lower half. does anybody know if that is true. Also trying to find out how to tell what year the motor is if anybody could help me that would be great.<br /><br />Thanks,<br />Keb