What exactly do Rear crossmember braces do? I`m re-doing the rear end, arms with a new sway bar, springs & shocks and wanted to know more about the braces and the benefits to installing them. Thanks

I think you are talking about the triangulation braces. Very simple installation. They connect the front of the upper control arms to the front of the lower control arms at their mounting points. They use the existing bolts for the control arms. Strongly recommended if you make any power and I believe were intalled from the factory on the higher perfromance cars.
Heres the ones I have:
http://dickmillerracing.com/store/page10.html
scroll to part#NOS-7029

Hotchkis has them too:
http://www.hotchkis.net/6872_gm_abody_trailing_arm_mount_braces.html

Probably many others too.

What exactly do Rear crossmember braces do?
Prevent stress fractures in the frame.

They provide stability under shock load by triangulating the load points. Gm engineered them for high torque usage. I understand the big blocks all got them and manual transmission cars. Don't have to spend your money on repops or spendy originals is you've got access to a welder. I cut 3/16 plate for the eyes (roughly 1 1/4 x 3 in.), installed them and then tied them together with 3/4 dia. x 1/8 in tubing. If you don't use them and use your chevelle as it was intended it will likely wheelhop. Boxing the trailing arms, the above braces and poly bushings go a long ways in tightening your rear.... the car's that is. :thumbsup:

Excellent info guys, thanks a bunch.

http://cs3automotive.com/uploaded_images/hot1400_installed.jpg?IctQual=100

I have free shipping on most Hotchkis parts ;)

http://cs3automotive.com/index.php?a=PROD:1437