I put Spartans in the front and back. The rear Spartan doesn’t make much noises and they work like a charm... all four tires stay hooked up. I have beat on them pretty hard and had no problems. I installed them myself. Used YouTube as a guide. The operation was pretty straight forward. There are no shims holding the diff carrier. The hardest part was pulling the rear axle shafts. I bought a 12 ton hydraulic pulled from Harbor Freight to remove them. The spindle bolt that holds the front hubs on is a weird size socket. I ordered the recommended size and still had to machine it for proper fit.