I’m pretty sure those shift pivot pins have some kind of internal propulsion system, like a Mexican jumping bean. (Remember them? Whatever happened to them?) I took a ’56 15 hp apart and SAW the pin, was AWARE of the pin, thought I put it in a little cup with other small parts and STILL lost it!! I never DID find it and finally made a new one out of a piece of stainless round stock.
Long live American manufacturing!