While the "truss" style upper control arm mount is reasonably well designed and fairly stout, it is still doing the job that was shared between two upper arms previous. I've seen a lot of carnage in roll overs so I wanted an extra bit of strength between the truss and the axle housing. The weld around the two cut off ears is a poor bond since it is to cast material. By filling the gaps with weld, that adds a mechanical connection that won't let it more laterally. Then, even if the welds crack all the way around like some cast welds do, they won't crack in a perfectly straight line that would let the truss lift straight up off off the ears.
Of note- the cracks or joints at each of the bends in the truss flanges should not be welded until last. Welding closes them up and pulls the two ends towards the middle and the truss won't fit.
The appearance of the pieces we weld on should also be noted. They are a uniform gray, that's because we have sandblasted each piece. I wanted a good key for the finish paint and then I wanted a good key for the weld through primer which is a high zinc content version in this case.
Which weld through primer are you using?