My previous NG900 and current OG9-3 had the same problem of the shift knob coming apart. The rubber shell tears away leaving the jagged and very rough nylon part that is very awkward to handle. In my previous SAAB i just wrapped it with some cloth tape but now i have a 3D printer and decided to make a replacement. I've been using this knob for half a year now and it's pretty good. The shape was done by eye and loosely based off the old rubber boot that came off. A "SAAB" and a griffin were debossed into the surface for the purpose of filling them with colored resin to make the shape pop.
Please note that as-is the model is slightly too tight and does not fit on the nylon part. I've found that printing it at 102% seems to give a pretty good fit.
STL and 3MF files included. Edit: looks like my 3MF file got butchered, so go with the STL, it looks fine. Edit2: the 3MF looks fine in Cura, so it must be a bug with thangs.
More about this project on my blog at: https://brimmingideas.blogspot.com/2021/10/3d-printing-new-shift-know-for-my-saab.html