[Michael Corsetto]

I think I see a snap ring right in the middle of your output shaft. This snap ring will be close to, if not entirely, impossible to install.

Other options:

E-Clip - Ok in this application, but not recommended. I don't like transferring torque through any sort of groove, especially the deep grove required for this application

Shaft Collar - Not the best, but could work in this spot

Change up your shaft retention locations. Review other team's CAD's to see their arrangement of shaft retention on a typical output shaft.

Please post results.

-Mike