When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Might help to know specifically what truck. Last shackle bolts I did was/were 35 ft lbs and then back off to the first pin hole. In other words, snug but free. U bolts torque will be determined by size of the bolt. Like mentioned, service manual for the specific truck. A U bolt torque chart would work as well.