Before the kit arrived, I purchased an iron 3.55 ratio differential from a wrecked 2018 Mustang with 17k miles. Since I am using the Mustang’s independent rear suspension, this is the required differential. I could have purchased new, but these things are tanks and I saved a few hundred bucks. Becuase it is used (the only used part I will use), I elected to pull and replace the axle seals. With a puller it wasn’t a difficult task.
Before replacing the seals, I prepped the housing for a coating of POR-15 with their Cleaner and Metal Prep products. The POR-15 went on easy with a brush. Wear a mask with this stuff!
Quick tip for POR-15 users: After opening POR-15 it can be hard to reseal and this stuff can rapidly cure in the can during storage. To avoid that, consider never “opening” the can! Use some self tapping roofing screws with the rubber washers to create pour and vent holes. Replace immediatly after filling your paint cup.