Are you sure that you have steel control arms and not aluminum? They are significantly different in design (even if they’ve been painted).
Also, the larger stub can be put into the smaller hub upright by spreading the clamp area slightly (not an easy job, but doable). However the smaller stub can’t go in the LNF upright because the hole is physically bigger and can’t clamp enough to hold the smaller stub.
Also, the larger stub can be put into the smaller hub upright by spreading the clamp area slightly (not an easy job, but doable). However the smaller stub can’t go in the LNF upright because the hole is physically bigger and can’t clamp enough to hold the smaller stub.