Farmall 400 - pto drive gear teeth munched

[ChampagneNBeer]

Hi All,

I have a Farmall 400 and the bolt that holds the pto drive gear in place (this bolt threads through the gear and onto the star shaft) decided to walk itself free, fall to the case floor and chew up all the drive teeth.

I believe I have to split the tractor to resolve but wanted to see if there was some other way I could fix?

If no other way than splitting, anyone know if special tools are required and if it is a difficult job? Anything else I should check while poking around in there?

Lastly, anyone know how to identify the correct drive gear? Seems they changed over the years and some even have the same number of teeth, but different angles?