New leafs, new 50 mph vibration

I don't know if this was coincidental but before getting new leaf springs in I didn't have this vibration I can feel from seat and steering wheel. I can also hear the dash rattling. The springs seemed to have quieted whatever driveline noise I had decelerating from 45 mph to 30 mph but now I got a vibration. Tires are new, maybe 5000 miles on it. One is newer because it was replaced under warranty. They were same tires that were on before new leafs. They did an alignment on my truck which has been out of alignment for a while but don't see how being IN alignment would cause a vibration. I'm thinking its my driveshaft but I don't see how new stock height leafs would cause any change. It has a new carrier support bearing that was on before new leafs. No lift so I don't see how the angles are off. Does the dealer touch the driveshaft while replacing leafs? Don't see how its necessary.

 

I would check the torque on the U-bolts. Mine didn't seem all that tight, and as soon as I tightened them, it felt a lot more solid.

 

So 73 ft lbs not 37 ft lbs right? Maybe the tech went with the error printed in torque specs that says 37 ft lbs. What size is the nut by the way?