My Tahoe is a testament to the quality of Genuine GM/AC Delco parts. Out of all the work I did in my build thread, not one part has failed or was bad out of the box. The rig drives like brand new, only better, with the Hellwig sway bar kits and the BBP tune.
That control arm experience is when I first learned of the three tiers of pricing, but, most importantly, quality with the AC Delco parts. Had I known then what I know now...
As for the UCAs, I have some ~3,000-mile-take-offs from a much newer ('21?) truck, removed for a lift. They're aluminum but are the same otherwise. The ball joints are my concern as they're either longer or have a different taper than those for the iron variants. I haven't investigated enough yet. But, I got them, along with some struts and shocks- all for free. I really just wanted the struts for the top plates and dust boots. Those, alone, are a couple hundred bucks in OE parts.