I don't know about 2WD. All my experience is with 4WD.
Far as I know, there's THREE kinds of lower control arms; and just to be more complicated, there's two widths at the bushing end for the upper arms..
1/2-ton and 6-lug 3/4-ton trucks use upper control arms with the "narrow" spacing. 8-lug 3/4, and 1-ton trucks use the wider spacing on the upper arms.
K1500 vs. K2500 8600 GVW upper control arms.
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Stamped lower arms are just that--formed and welded sheet steel from the bushing end to where the ball joint attaches using four fasteners. The OEM fasteners are rivets; replacement ball joints come with four bolts to replace the rivets.
Bolt-in ball joint, removed for obvious reasons.
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...and the control arm it came off of.
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A newer version of the stamped arm apparently uses a permanently-attached (welded?) forged end with a
press-in ball joint. I've never seen one of these in person.
And of course as we saw in the photo some posts back, there's the fully-forged arm, which also uses a pressed-in ball joint. This joint may or may not be the same as the pressed-in ball joint in the stamped arm with the permanently-attached forged end.
It's my understanding that the Polyurethane bushing inserts from Energy Suspension or ProThane (or, I suppose, anyone else) will fit any of the three styles of lower arms. The stamped arms either re-use the existing outer bushing shells; or you press out the original outer shells and press-in the "new" outer shells. The forged arms don't use outer shells, but--apparently--the bushing insert shape is the same as the others.