One dirty little secret of the motorhome industry is that many RV manufacturers simply ignore suspension issues. This often results in poor handling, even to the point of some folks not even being able to drive the motorhome that they just spent tens or hundreds of thousands of dollars purchasing. The major reason is the chassis manufacturer (Ford in the case of the E series) simply does not know what the RV manufacturer is going to add to the chassis - or even how they are changing it - such as lengthening it. So it is impossible for Ford to know what tuning must be done on the chassis.
In reality, this responsibilty falls with the RV manufacturer, but I doubt many pay any attention to that requirement. In fact, I wouldn't be surprised if there were no engineers on staff at the RV manufacturer that has experience in suspensions.
Rather, they push the coaches out the door as fast as they can, and leave the RV owner to fix whatever problems they caused. Another great quality concept from the RV industry.
To be fair, some motorhome manufacturers do pay attention to suspension components. Jayco (J-Ride) and Coachmen are two manufacturers that do work on the chassis.
Quite often, more than one single thing must be done to the RV to improve it's handling. Popular fixes include heavy-duty anti-sway bars, steering stabilizers, air bags, heavy-duty shocks, and so on. In reality, the best handling rigs probably have had several improvements of this type made by the owner, so the real question is; which one to do first, and which one will have the greatest improvement, as well as the most bang-for-the buck.
Much of the "scuttlebutt" on the internet has suggested the first approach, at least for an E-Series chassis, is to upgrade the sway bars; however, many owners upgrade the steering stabilizer first - perhaps as it is a simpler fix. Which one is better is debatable (but I favor the anti-sway bar first). One comment I read that seems to bring this point home is that;
Of course this is rhetoric in part, but there is also some truth to it.
For my coach, a 2011 Ford E450 with a 11 spring rear axle, the appropriate Hellwig Sway Bars were; 7718 for the front, and 7180 for the rear. Different years or spring configurations differ. Contact Hellwig for the proper numbers for your application.
Typically, you will have to order the sway bars unless you are lucky enough to find them locally in stock. For the on-line retailers, When comparing prices, consider shipping.I found shipping to be anywhere from free to as high as $75 for some retailers (the actual UPS cost for shipping in the US is less than $30 in most cases). If you see a real low price on these, make sure you factor in the shipping costs, as they can be significant.
In addition to Hellwig, other manufacturers, such as RoadMaster produce RV swaybars for the E series chassis, but I can only comment on Hellwig as that is what I used.
In conclusion, the anti-sway bars were a great improvement. I no longer have to saw on the steering wheel or hold it with a white-knuckle "death grip". I can even let go of the wheel for a few seconds and the coach will maintain it's heading. What drove like a dump-truck now drives like a SUV. While not car-like (which I am not expecting anyway), but much improved.
Popular Hellwig Anti-Sway Bars for the Ford E-Series Chassis.