Cat 212 starter

Was wondering what the correct number of teeth would be for the starter for a Cat 212 grader 79C series(D 311 direct electric start)? I understand that there's an 11 and 12 tooth configuration. Also, will either the 40 MT and 42 MT work?

Now that the 11 tooth is available I'd go with that although either one will work.
(RH helical)
You can use either the 40MT or 42MT but the drive end housings are different and requires a special housing for the application. The 42MT housing uses an "O" ring seal, the 40MT does not.
The 42MT is later production with round solenoid that doesn't stick out as far.