Upper Control Arm Questions

[TheJet-09]

Two questions:

1) I see control arms with slotted shafts and those with slotted shafts utilizing a "slug" to apparently hold them in place. My question is whether the slugs are necessary (they can be pricey themselves and you don't know which ones you need until you check caster), or do the slotted shafts without slugs stay put where they're bolted?

2) When I last bought upper arms from Mastersbilt, they said I needed a steel shaft on the LF because aluminum would bend. Do most agree with that or has anyone had any experience with an aluminum shaft on the LF bending?

Thanks in advance!

[MBR Performance]

We've bent several aluminum shafts on the LF without even hitting anything. The arm is to long and has to much leverage.

[Matt49]

I personally prefer aluminum on both sides. I would rather bend the cross member than bend the frame uprights after a hit with a yuke tire.
We use the OutPace uppers that are slotted and do not require slugs. Instead, they have a plate that locks the upper in place independent of the bolts that secure it to the control arm. They are a pretty nice piece.
I could go on and on about it but I do not believe in setting caster with the lowers unless it is a true two-piece (strut style) lower control arm.