I believe the long rod TX's ended with the hydraulic clutch. Other than relocating the wiring for the reverse light, you can use either TX in most any Alfa. The later TX's also deleted the push-down-for-reverse shift lever (with screw-on knob)in favor of a side-push spring gate (with push-on knob).
Lots of folks fail to replace the square o-rings for the shift levers, and the TX slowly leaks TX lube ( mostly vapor) into the clutch housing. The short rod TX solved this issue, likely why it was introduced.