Not the reason. Odds are you wont twist all 8 nuts off the stock U bolts without twisting or breaking at least one. The U bolts aren't supposed to be reused anyway because they get twisted which weakens the steel.
The stock nuts are what they call scored nuts. Tiny square indentions that distort the threads. Use a torch and heat them quickly and a impact will zip them right off but ... Got torch ?
Lifes much sweeter if you'll plan to cut your U bolts and install 35 bucks worth of new ones.
Like I stated before... if the rear was dropped at the spring hangers, you're golden. Install it springs and all.
