Manufactured by Teraflex. The TeraFlex JK/JKU Front Upper Knuckle Gusset Kit is designed to reinforce the weak knuckles on JK/JKU Dana 30 or 44 factory axles. This prevents unwanted bending or breaking under extreme conditions. � Sold in pairs NOTE: � Does not fit Rubicon Recon w/ Dana 44 front axle w/ 3/8� wall.