Here is the latest of where i am at with my car
My chassis was not only tweaked, but it was actually bulging from the center, so i shopped around, was curious about your aluminum chassis Marv, but then i found the Exotek chassis.
http://www.exotekracing.com/sprint-spx-pro-chassis-set/
I haven't tried the car yet (friday is my first test), but already the car is MUCH stiffer, and straighter.
There are shims everywhere, i rebuilt the diffs like on this thread, i rebuilt the car from the ground up, i even had to grind out the plastic piece infront of the motor so i can fit my brushless motor, the tabs were rubbing on the frame.
Also - Marv, for the steering, i grinded down the front c-cups a little, but i actually grinded down the 2 steering hubs. I used a 1/8" bit on my dremmel and removed enough so i can do a full lock on my steering now.