Rare Parts RP11911 Ball Joint Extreme duty quad steer ball joint. Mounting plate is cut from 1/2" thick steel. Rare Parts design offers a threaded in ball joint to the plate. (The original ball joints that came on the quad steer truck were non greaseable and they used nylon internal components) Rare Parts quad steer ball joints offer steel on steel design and they are greaseable. 100% made in the USA This ball joint contains a massive 40mm full ball stud giving it a 24% increase in wear surface over OE. Heat treated components for increased strength and better wear characteristics. Tested and inspected to exceed OEM specifications. Exact replacement, no modifications necessary.