You definitely need to torque U-bolts. In fact most spring shops recommend NOT reusing U-bolts. I don't know what the spec is for a '46, but the spec for u-bolt torque for AD (47-53) 1/2 ton trucks is 75-90 ft-lb. I would suspect that a 46 would need the same. But someone will likely come along with a definite torque number for you.
