I too believe it part of the syncro and it means you don't drive the car. there should be no way for that to escape its assembly so that means there is something ready to come apart in a big way. take it apart now and fix it before another one falls out and jams and scraps the whole box. you got very lucky just now finding that... build on that good fortune...Drained the gear box this weekend and found this little part attached to the magnet on the drain plug when I unscrewed it. Any ideas what it is or where it belongs?
First off, thanks to everyone who has chimed in so far.About the only way that expander or spacer (call it what you will) could come loose and fall out is if that gear is so loose on the shaft that it could move far enough to let the thing fall out. There is no way that you should have that kind fore and aft movement on the gear shaft. Only other way is if it was dropped out unknoticed during assembly and has been loose in the bottom of the case ever since until it finally ended up in the magnatic drain plug. Do you have a malfunctioning gear (syncronizer wise) in your transmission?