For anyone ordering ouo trac bars with the 04-08 f150. The site says its a 3 5/8 diameter axle tube. I ordered them and got curious and measured my axle. It was 3 3/8 tube. I made them aware my 06 with 9.75 rear has a 3 3/8 axle tube. Luckily they had not shipped them yet and are going to change the lower my brackets to the 3 3/8 ones. Yes they are pricey but ive seen alot of others that have broken, and id rather buy one set than multiple. Ill put up pics when installed.