New U bolts??? Do you remove the U bolts to the leaf springs to install? If not i see no reason to touch the U bolts. Just make sure they are torqued to SPEC.
DO NOT OVER TIGHTEN ANY U BOLTS AROUND THE AXEL TUBE, YOU CAN CRUSH THE TUBE. I have an 8 3/4 housing to prove it. AND somewhere in the FSM it notes the same. If the kit comes with U bolts to bolt it to the housing and they are NOT flattened in the bottom of the U, I would buy some that were flattened. A lot of psi in the tiny contact patch a round U bolt makes with the housing tube.
No alignment needed unless you remove the rear U bolts and the locating holes in the spring perch are elongated. Even then the amount of change will probably be negligable.
