Only 3 companies use Nachis that i know of for upper A arms, which is Cparks Powertrix A-Arms, AMZ Front upper A-arms, and of course the original Midori/TBO A-arms....I dont know about SPL's tho. PS AMZ also offers a Sealed bearing version also so its completely weatherproof from the elements, some other arms are only Shelided bearings which are not completely water/dust/dirt proof.