So I did confirm (prior to ordering) that I originally had the stamped steel UCAs. No fault of Kryptonite since I didn't order directly from them, I was sent cast UCA joints. I just ordered the proper ball joints directly from them this morning but it'll be 2-3 weeks before they arrive and since I don't feel like undoing the work, the truck will just stay on jacks in the garage until the correct joints come in. Maybe I'll take the time to make sure my wheels/tires will fit.
I don't believe you need to do the lowers at all. But I'm a fan of going the extra mile, so I'll like to see how it turns out.
Also, I don't have the X31 package. So you may very well be right about that