To bad about the prang, but you know why your pranged & you might use the system by Kenny Roberts being "in slow & out fast" which is exactly what I use & do.
The drawing Vash sent is NOT showing any farther then the spline of the shifting part. What I would highly suggest is that you visit someone that sells your make of m/c & see the parts man for they can bring up EXACTLY what you need to be replaced & in the end it will be quicker & less costly then guessing what said part is & ordering over the 'net only to possibly receive the wrong item. Time to wait for said part from the dealer is around two days. It was four days in my case for the dealer had to mail it to me.
On that spline (showen in the drawing by Vash) going into the gearbox section is probably the part damaged, in your mind, & it is that lever with the pivot on it that, is probably held by a 10mm bolt with a 10mm lock nut & bolt to snug all up. After that it is the extended rod (left handed thread in this case---while right handed thread at the rear gear change lever) going to the rear gear change lever also with a pivot part only. IF it is that part then make sure you obtain a 12 or 10mm left handed nut so you can snug up both ends of the extranded rod.
All will sound a bit mixed up, but once you go to the m/c dealer parts man & see what to order in then all will make sense. It is just that some do not realize sometimes on a bike one can come across a left handed thread/nut for a specific job.