1999 1.9tdi gearbox linkage/selector

the linkage ontop of my gearbox rounded off today, the nut must of came loose and rounded the splines, after been quoted ?200 for a new one form vw i went to the scrap yard and got one for ?20 i pulled off the black bit with the splines on then undone the 2 bolts holding a cap over the shaft coming out the box with the splines on, and pulled out the gear s elector from the box, now my question is will this go straight into my gearbox how do i put it in as it has like keys onit, any help please on how to fit them as i dont want to damage my gearbox,

regards tom