I would like to comment on the topic of stretching the torque rods with flat stock or some other method.
Think of the photos you have seen of the extreme amount of articulation the rear bogie of a Deuce can accommodate. One wheel all the way up and the other all the way down, with the other axle similarly crossed up but in the opposite direction.
Now think about how compliant the torque rods have to be to do this. There is just no way that all of the required movement is coming from that rubber bushing flexing. The difference is made up by the torque rods themselves twisting.
It turns out that an I beam section does a good job of flexing torsionally. Once you extend the rods, you probably lose most if not all of their ability to flex properly. The same goes for replacement torque rods that are fabricated from DOM stock or whatever else was laying around.
Yes, even a bodged-up torque rod can twist. But how much force does it take? If much different from stock (don't think for a minute that the engineers who designed this suspension did not calculate this out to 2 decimal places) then you might be transferring stress to another component that is not designed for it, and ultimately something else fails. Even more likely, the builder wants to 'make sure these things are strong' so they overkill the extension and the weld, making the extended rods so much stiffer that they do not want to twist at all. Again, this transfers load to other parts of the suspension (for example, guaranteeing that a rubber bushing will rip apart) or perhaps even fracturing the 'new' rod.
I know that some guys have extended their torque rods, however they did it. And I know that most if not all of them will proclaim that all is fine. maybe. Or maybe no one wants to admit an error. Or maybe the way they use their trucks, they have gotten away with it. All of these things can happen.
But to me, the articulation capabilities of the stock rear suspension is one of the amazing thing about these trucks. I could not, myself, ever do anything that could take away from the original design.
That's me, YMMV, free country, it's your truck so do what you want with it, yada yada: I get it. But, something to think about, perhaps.