Not sure of the difference from a rear end on spings and u-bolts,..but I was in a accident where we got t-boned right in the rear axel at 60+ mph and it just sheared one side of the u- bolts.Drove it home dog tracking and put new u-bolts on it and a axel and was fine.The car that hit us was totaled and the truck just looked like it was high centered and had minimal bed damage at the bottom in front of tire.It was a pretty good impact as it spun us 2 1/2 times in a circle from the impact.I would make sure and use grade 8 or better and make sure that bottom plate has a locator pin or welded.