Hi jdw,
A sway bar and stabilizer bar are one and the same.
BEFORE YOU BUY ANYTHING, first get a front wheel alignment, compliments of Ford. Call Ford customer service for instruction. When you go there, have a full tank of fresh water & fuel, all your gear, etc. Try to simulate the weight as if leaving on a trip. If you want to go the extra mile, add weight to simulate driver and passenger. I threw in some weights from exercise equipment, set on the floor behind the two front seats.
About your 2011 chassis not having availability, I suspect the on-line information has not yet been updated to accomodate 2011 model years. I advise to call Helwig and Roadmaster direct. They may say to simply order 2010 parts.
I also advise to have both the rear sway bar and rear trac bar installed at the same time. This because the installer will need to adjust the position of the sway bar to accomodate the trac bar. You would not want anyone to mess with sway bar mounting hardware twice.
If your budget is very limited, start first with rear sway & trac bars. That will address the worst of your handling troubles. Immediately following would be a front sway bar. If you still have issues, then do the shocks and steering stabilizer.
As you know we had everything done all at once which made a "MEGA" improvement in handling. Our rig is a real joy to drive and ride in. No more "Drunken Sailer".