That's why I invented what I did Matt
Differences in cartridges are:
- opening direction (clockwise or anti)
- dia of spindle (splined bit - 7.5, 7.6, 8.0, 9.0, 10.0mm)
- number of splines range from (15-56)
- splined length (5-12mm)
- height of spindle (22-120mm)
- whether it's threaded for a shroud (yes or no)
- depth of seat (inside depth of tap 1/2" from 21 - 26mm, 3/4" 20 - 27mm)
There are more, but calculate the above & it works out at around 1,000,000 permutations. Reality tho is around 2000 so far found for 1/2"...