Leaf spring shackle bolts

Also it might be rear end specific.

8 3/4" u bolts are way less torque than you would think like 45 lbft IIRC and if over tightened WILL crush the housing tube.

I have the photos to prove.

ALSO...
if in an 8 3/4 DO NOT USE ANY U BOLTS THAT DONT HAVE THE FLATTENED AREA IN THE "U"

Round u bolts have point load that will crush the tube at lower torque than spec.

I also have photos to prove it.