[The cap'n]

If you have the old gear from this engine, you can look for the number. If you're putting it together from scratch, there's a procedure in the manual for determining what size you need. Unfortunately, you need access to several sizes of gear in order to select the right one. It all has to do with geat lash, too much and you'll have noise and rapid waer. Too little and the gear will wear out in a few miles. John