When I bought the truck it had 315's on it. I replaced them with stock tires before I removed the lift and the transmission still shifted the same. It didn't change until I removed the lift. The truck only has 49,000 mile on it so I wouldn't think the ujoints would need to be replaced but who knows. I crawled under the truck yesterday to see what the shocks were set at. They all arecset at 5. At least I think they all are. The right rear was installed backwards and I can't get to the dial. I'll be fixing that this morning and try dropping the rear down to 2 and see how it rides.