Upper Control Arms Question

I've read multiple times that "you need aftermarket upper control arms once you lift past x-inches". What dictates the need to replace the upper control arms? Is it based purely on whether the truck can be aligned properly with stock UCAs or are there some other symptoms to be aware of that may indicate UCAs are needed even if the truck was aligned? I just installed 6112s on 1.9" setting with 1 CB shim per side. Drives fine. Alignment sheet attached for entertainment purposes.

 

Should not need them at 1.9 inches of lift. Some recommend them only past three inches of lift. But here's the caveat, is the steering wondering or twitchy? If it's centered and not darting left or right with a light wind or light road crown then you're fine. Mine at 2.5 was driving straight but very darty left or right with minimal steering input. Needless to say that even though not necessarily recommended I went ahead and installed JBA upper control arms, and it made a big difference. Drives like it's on rails.
Do make sure that your caster is maxed out on the right tire and that it is half a degree lower on the left. This is paramount on leveled trucks.