I don't see the year model of your Freightliner chassis, but here's what I've experienced with my straight axle Freightliner (2000 model year).
Sloppy steering: Had front end checked all components good. Had front end aligned. Still had some sloppy steering. With a helper, checked the "slop" in the steering gear box. After a minor adjustment to eliminate most of the free play, the steering was much better but still experienced rut tracking where the tire follows the ruts in the road. Many Freightliner owners have had to adjust the steering gear box. The adjustment is on the side of the gear box, and there is a hole in the frame member allowing access to the adjustment. If you do this, be careful to leave a little free play to avoid rapid wear of the gear box.
Installed Steer Safe: Rut tracking eliminated. No other benefit experienced (but no blow outs and controlling a blow out is Steer Safe major claim). The DW helps drive, and she noticed the elimination of the rut tracking and the more precise steering.
I bought the Steer Safe used from a follow rv owner, and it's been on my motorhome for several years. I see no corrosion on the springs.
The motorhome is much easier to drive now.
I have no experience with the caster wedge, but a good truck alignment shop should be able to install and set caster. The steer safe is easy to install so you can do that yourself.
Fred
