Yes, as long as the old U-bolts are in good condition, they can be re-used.
I don't agree with that. For safety reasons U-bolts and nuts should always be repalced, never reused. It's not worth the risk.
Here's an excellent resource and explanation http://www.eatondetroitspring.com/reinstalling-ubolts/ "The reason u-bolts should be replaced after they have been torque is because the threads are rolled, not cut. Because of this the threads are distorted when torqued. This distortion will not allow the torqued to be maintained when the nuts are loosened then retightened."
Here's a video explaining the same thing:
And from a U-bolt manufacturer who also advises aginst reusing them. http://www.uboltsdirect.com/ubolts.php "We never recommend using your old Ubolts. If you were to re-use an old Ubolt, there could be a problem when you retighten the nuts. The nut tends to grab the old threads, and these threads have been weakened because of exposure to road conditions ie. salt and moisture."
Yet another version of the same from a reputable source. http://www.acespringservice.com/u-bolt.html "*DO NOT REUSE U-BOLTS* *Used U-bolts will have rusted and damaged threads from the previous installation. *A previously torqued U-bolt will suffer from distorted threads from the engagement of the deep nut. Deep nuts should be tightened once and retorqued, never loosened and retightened. *A used U-bolt may have suffered from fatigue as well excessive stress since achieving accurate torque with commonly used impact wrenches is very difficult."
