Possibly mis-communication. When I read "control arms" I am confused. The K models have leaf springs on all four corners. I really don't know what you meant. I don't know of any control arms and I don't know of any coil springs. So your statement about K10 is in error. I think you are trying to say that whatever ball joints are used in K10 or K20 could possibly be the same size as C10 or C20. But there are no replaceable ball joints on the components you are asking about. Hence my suggestion of DOM. Maybe that's where you are going with finding ball joints.
DOM is used because it is very strong due to it's manufacturing method, as in: D rawn O ver M andrel. It is hollow and threadable with thick walls. Can't get that with seamed/rolled/welded. Most links are solid forged steel or bar stock. The DOM material allows for safe, strong, modifications to steering systems.
The method I'm thinking of for a drag link is DOM tubing with tie rod ends not ball joints.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| 
