[Bobcat]

Hoofa , Mrmustang , at the risk of having both of you on me , IMHO , I think you are both right . After looking at hundreds of rod end failures on sawmill equipment throughout the country , I saw identical rod end failures ... all at the juncture of the neck down area where the the thread starts . Failures were mostly traced back ( assuming the rod diameters and material were correct to start with ) to bending forces transmitted to the weakest point and over extension/bottoming out of the equipment the cylinder was connected to . Generally at that point ( full extension/full compression ) , the equipment placed not only a pulling/tensile/compressive load on the rod end , but also a bending moment . I realize that a hydraulic cylinder isn`t a shock , but the similarities are pretty darn close .
In a very few cases , it was because the tool used to cut the threads was too sharp and created the stress riser ... which is why we used rolled threads.
We normally solved the breaking issue by going to a bigger thread (full thread) , adding a spacer to move the load away from the weak neck down area , or in extreme cases , a bigger rod . However , all of this also went along with correcting the over travel and misalignment .
Am I 100% correct ?? Don`t know , just 20 years experience in the cylinder industry ... and again , I think you are both going down the right road .