Well I finally had a chance to investigate the clunk I was getting from my rear suspension and it is not good news at all. I found the problem immediately, the passenger side mounting bracket and backing plate had torn itself from the subframe. Here is a pic of the bracket just hanging off the bar:
One of the subframe where the bracket tore itself free:
Underside of the backing plate:
Now as some you may notice, the upgraded backing plate was already added but I think 99.9% of the breakage occured prior to the upgrade. I spoke with Terry Haines about it today and he believes that the stock bracketry clamps hold the 24mm sway bar bushing too tightly and does not allow the bar to twist like it should, this causing the bar to put undue stress on the subframe and backing plate.
So to those of you with the Aussie bar I'd highly recommend getting the backing plate welded on ASAP and if you have not installed the bar yet, do the uprgraded plate at the same time. To those that used the stock bracketry for a while, check the stock backing plate thoroughly for damage before you get the upgraded backing plate put on.
For my car, I'm going to have Terry drop the rear subframe and mount new, higher strength backing brackets to insure that I won't have this problem again.
Learn from my problems, get those upgraded backing plates put in ASAP!!!!