The intention of this modification is to remove the existing stud from the trailing arm and replace it with a bolt and nut so that when or if the bolt breaks then there it is simply a matter of unscrewing the two pieces of the bolt and fit another one. There are two options with this modification, one is to drill a hole in the backing plate to make it easy to remove the broken piece bolt through the backing plate by just removing the wheel, brake drum and brake shoe. The other options is not to drill the hole and when the time comes to remove the bolt, you have to remove the wheel, drum, shooe, wheel hub and bearing and backing plate.
First up you need to go shopping for two(one for each side) 3/8 UNC x100mm HT or Grade 8 bolts and two 3/8 UNC Nyloc nuts, or equivalent.
When it comes to jacking up the car it is best not to lift the wheel right off the ground as this can dislodge the suspension and get dirt in around the ball and cup so just raise the body enough so that the as you remove the existing stud it will clear the bottom of the subframe. Depending on the shock absorber fitted you may need to undo the top mount of the shocker to allow it to fall far enough to clear the subframe. Loosing the top mount is also a good idea to give you a little more room to move it off the stud.
To remove the stud you first need to undo the nut, 9/16 spanner, and slide the shocker off the stud. Grip the stud in the middle, so as not to damage the thread, with a pair of vise-grip or good pliers and turn it anti-clockwise(looking at it from under the Moke) and un-thread the stud from the trailing arm.
Fit the new bolt, including washers, through the shocker and into the trailing arm which should be easier now than the removal however keep an eye on the bolt coming out the other side of the trailing arm. You want to have the bolt just protruding with no more than a single thread or less showing so that it can help you locate the nut in the right place. Unless you drilled the hole in the back plate, you will need to hold the nut between the sides of two of your fingers and reach in and place the nut over the exposed bit of the bolt and hold it there while you continue to turn the bolt further in and thus thread the nut as well.
The head of the bolt should stop firmly against the shocker before the other end of the bolt reaches the backing plate. With the shocker firmly held by the bolt head, use a second 9/16 spanner and tighten the nut behind the backing plate up firmly against the trailing arm. This will hold the bolt in place and lessen the movement of the bolt cause by wear that may have occurred with the stud over the years and importantly it gives you something to undo to remove the bit of bolt if it should break.