rear suspension for Autox

I suggest tweaking your tire pressures (more in the front and less in the rear) to gain a little more balance by reducing front grip and increasing rear grip. If it is still too tail happy then I would disconnect the rear sway bar. That will reduce the roll stiffness in the rear and tighten the car up. A panhard bar won't really help overall cornering unless you play with the attachment heights a lot to find the optimum roll center height. You can always try a combination of sway bar and air pressure but do one at a time then test so you know what adjustment affected what result.

Oh, do you mean traction bars? Those will kill your cornering. As soon as the bar hits the spring your spring rate goes through the roof and that will make you oversteer even worse.

No, the Shelby traction bars will bind and basically cause the infinite increase in stiffness that Que is talking about. I ran these on my '67 for a while (without a rear swaybar) and the car got really loose once it was fully loaded up.

Look at putting on a 1 1/8" front bar and try no rear sway bar. My car is fairly neutral with that setup (4 1/2 leafs in the back and 620 lb coils in the front) after the traction bars were taken off.

There are more radical changes you can make, but try those first. Remember, seat time is the best way to get fast!

More info please! Is it under braking, mid turn, acceleration or just all around?
You could go with a TrueTrac if you have a limited slip or Locker.
You should upgrade to heavy duty shackles and harder bushings (Delalum) if you don't already have them.
Do you have adjustable brake bias for the rear?
Rear sway bar is not always a good thing as stated above.