98DAKAZ - If I remember the measurement correctly, I believe I already have a ~32mm front sway bar. When I look online its the biggest one I can find. When I have time to go to the local Pull-a-Part I'll remeasure to be sure.

 

Don't be surprised when you find the rear bar is a smaller diameter than the front. That's the way it's supposed to be. If you have a 32 on the front, you'll want to get a rear bar off a truck that also has a 32 on the front, unless someone here can post the rear size that matches. I don't know what it is.

 

I thought I'd come back and update this thread as I have since fixed the problem.
As Vimes suggested, it was the tires causing the massive change in body roll. I switched to Hankook's Dynapro AT2 255/65r16 and it stiffened up instantly.