Well, I towed my first really heavy load since the rear spring upgrade, and I have to say it was interesting. I hauled a 60kw generator on my gooseneck for a total weight of right around 8500lbs. The diesel had the grunt to get it moving, but every time I had a change in speed there was a sort of wave that I assume was the rear springs twisting with the torque being put into the axle. I had this issue before, due to weak springs that wound up bending towards the front permanently. The new springs I put in are heavier and in better shape, but now I have 375ft/lbs of torque on tap so the load is much greater.
I know some people have some pretty beefy engines in their trucks, so what are you doing to control axle wrap? I don't want to trash another pair of springs, another driveshaft, or another axle yoke.

 

The May 2013 issue of 4Wheel & Offroad magazine has an article comparing spring-under vs spring-over configurations. They tout the spring over for increased ground clearance but the inherent effect of applied torque as illustrated below. Their recommendation is to add antiwrap bars.

 

I'd suggest putting traction bars on the rear axle to help it from having axle wrap like shown above I've seen alot of people make them there selves i plan on making up a set for my diesel pulling truck this year

 

Add a stack of overload springs.

 

My old springs had that bend permanently-
I have the stuff to build a link like that, I might even be able to repurpose one of the radius arms I was going to use on the Courier project.
Would it affect strength to weld to the axle housing? That one looks like it's welded, but usually you see that sort of stuff on some lifted to the sky mall crawler that will never see a trailer or heavy loads.

 

As long as its a good weld and not cutting into the axle tube the strength won't be effected. Just got to watch the heat so you don't damage the seals or bearings. I've seen them on rigs that do alot of off roading and towing. My buddy has them on his truck and he mostly does trail riding with it and some towing. There is off road places that sell a kit to make them you can get them as a bolt around axle or weld to axle kits

 

2x with the above .. welding on the bracket will be far from the axle seals and D60s have enough meat to be welded on unlike the 8.8 where the axle tube is thin.

Anti-wrap bars appear very easy to make. In fact, Spike's "Muscle Car" show made a set for their retro altered Comet. They have to be identical so fab up a jig to ensure that it is. They welded some bolts to a table and I think they used polyurethane leaf spring bushings at the mounts.

 

Doing some looking, it looks like a lot of these guys are running a single link. I have a radius arm leftover from my Courier build, before i went with a different style, and it would fit the bill quite nicely.