Question About Moog Control Arms

[Silverado-Hareek]

I tried to search for my specific question but I couldn't find the exact answer I was looking for.  I just had Bilstein 5100 leveling shocks installed on my truck.  In going to get an alignment, we found that one of my upper ball joints is loose (driver side upper).  I currently have the aluminum stock control arms on the truck.  As you know, these ball joints can't be replaced without changing the entire control arm.  Rather than replace the entire control arm with another aluminum arm with a non-serviceable ball joint, I wanted to go ahead and replace both upper control arms with a better aftermarket product that allows servicing of the ball joints down the road.  I'm looking at buying the Moog CK "problem solver" series based on recommendations from others both on and off the forum.  It looks like these Moog control arms are iron.  My question is whether there is an issue or not with replacing the stock aluminum control arms with iron (change in metal).  Furthermore, if I leave the stock lower aluminum control arms in place for now, is there any issue with having an iron upper control arm and an aluminum lower control arm?  Thanks in advance for your help.

[Silverado-Hareek]

Update:  I spoke with Moog via email.  It looks like you cannot use their control arms if you have aluminum steering knuckles on your truck which I have.  Bummer....