Try here:
- http://www.trail-gear.com/suspension.html
or here:
- http://offroadsolutions.com/suspension.html

Not going to find anything bolted on, though.

Generally washboard road will not induce axle wrap, it is typically caused when starting out and the extreme torque on the rear axle causes the springs to twist upin front and down in back:

[Linked Image]

You can get a bolt-on anti-wrap bar from Bud Built:
- http://www.budbuilt.com/new/traction_bars.html

[Linked Image]