Sorry to revive a really old thread, but i recently was attempting to modify my p360 actuators, and had problems finding these things, and also didnt want to pay for a lot of 50.
Ended up creating my own STL file and 3D printed some, and they work perfectly, thought I would share them for anyone else in the future attempting to do the same.
These are 13.5mm which give more diagonal range, and 19mm long which resolves the crunchy noise.