as for replacements, the only ones I am aware of are the Brandwood and the current PBS style. The PBS style is the best shifter I've ever felt on a Spyder, but it not an east install. It CAN be done with the trans in the car but requires trimming the R slider and replacement of the nosecone, plus custom mounts. It's a lot of work.
The Brandwood was a nice solution when it was all that is available, but I fount stiff and notch, so not my personal choice. All of that said, a properly adjusted rod shifter works really well.
As for the pictured breakage, it may have been simple fatigue or it may have been a very rough shift coupled with fatigue, but either way I;d look at the bushing in the middle of the shifter also. It is located near the bell housing of the trains. If this wears out or deteriorates it affects rotation and shifting becomes more difficult and vague. This is when we usually see shifts having to be forced and not smooth.