While we're still on the subject of gear box bolts, let me restate the "torque" part. Do not just whack at them with an impact wrench and in fact most of the problems arise from using an impact. That is a hollow frame rail box you are crushing with the rear two bolts and a flate sheet panel on the front bolt.

Look up the proper torque setting for your vehicle and tighten the bolts to the specification.

Most of the frame rail repairs consist of welding a large plate over the crushed/rusted outer frame rail. The plate distributes the stress over a large area of unstressed metal. The same way the original design worked before metal fatigue weakened the rail.