2nd./3rd. Cam
Insert the 2nd./3rd. shift shaft into the case.
Push it all the way in as far as it will go (it will push in past the interlock sleeve).
Drop the interlock spring into the sleeve.
Press the 2nd. ball bearing into the sleeve (w/thumb or finger) against the spring. Continue to hold it down. Make sure the 1st. ball bearing is engaged in the neutral (middle) detent in the 1st./reverse shaft.
With your 3rd. hand, reach around outside the case, and push the 2nd./3rd. shift shaft back into the case so one detent engages the 2nd. ball bearing.
Insert the other taper pin to retain the 2nd./3rd. shift shaft in place (w/same admonishment as before).