I would think a uniball even a worn out one would be almost impossible to tear out from the race and you won't be able to tear the cup open allowing your part to completely leave the truck. A heim could tear and separate letting the parts fly off. Think of the mounting points also, a heim has a welded sleeve and the strength of attatchment is the depth of the threads where the uniball's attatchment is the strength of the weld with a potentially larger surface area. For the size and a reasonable amount of strength a uniball should also be cheaper and way cheaper to replace since you only need to change the guts....Curt
We have done both. The uni ball has one problem. It is harder to remove if you need to change it. They will both do the same thing. We use a 1.250" heim and have never had a problem. It is easy to change and it is also much faster to change if you ever need to. If you are in a race I would also prefer the Heim because you can change it under the truck. With a uni ball you would have to press it out and that would take way more time to do.