Is there a rear strut brace available for the 6th gen?
I have one for my 4th gen.

 

The strut brace is for the front struts. In the rear there is a stiffer anti-sway bar that replaces the original equipment bar (already in place). I have the Catmann replacement and find it is much stiffer than the original equipment.

Go here for some earlier discussion on this.
http://forums.maxima.org/showthread....3&page=1&pp=30

There was another thread here entitled "Rear sway bar for 04-05 Maxima" that is not longer working (I can't get the link to work). The last post was done on April 28, 05.

 

The rear uses a shock / spring setup. The top of the shocks bolt into what appears to be a cross member at the top of the rear wheel wells that is part of the body of the car. This makes a brace unnecessary since the top mount points of the shocks are already braced laterally. As SilverMax said, the beefier anti-sway bar is the necessary upgrade for the rear suspension.