Apparently, they are now working on an E body frame.
Greg
I really don't understand why there are a lot of people using the four link real suspensions. There is a lot of bind in these suspension due to the out of plane motion in the upper links. GM suspension engineers didn't even like these designs. A simple three or four link with a panhard bar (or watts link) get rids of this problem. Okay the four link packages much better, but these are custom application not production. A few more dollars spent on the more sophisticated design would result in a much better suspension.
