Our 2007 Phoenix Cruiser is built on a 2007 Ford E350 chassis, so I am extremely familiar with your situation.
The 2007 (and older) E350 chassis purchased by the RV manufacture, direct from Ford, did not include a rear stabilizer bar. If you have one, it was added later, either by the RV manufacture or the previous owner.
Your chassis has a front stabilizer bar, but it truly is an inferior design as well as inferior for the heavy duty motor home application. Ford wised up and redesigned the front stabilizer in 2008 which is still installed in a 2019 model today. If you look at the two ends of your front bar, you will see they pass through rubber grommets located in the lower control arms. The grommets wear very quickly which causes play that cannot be adjusted to be eliminated. You just live with the play which gets worse & worse, which renders the bar less effective. Adding fuel to the fire, the thickness of the front bar is designed for an E150 van, not an E350 motor home. It is too weak of a bar to keep a motor home stable.
So....
Going with Helwig bars is a good choice for affordability without compromising the heavy duty bar thickness & hardness rating. They are spec'd the same as the Roadmaster brand, but at a fraction of the price. To be clear about it, both front and rear Helwig and Roadmaster bars come with polymer mounts and bushing end-links that can be tightened as they wear.
I need to add that you may want to consider heavy duty shock absorbers. I "LOVE" the heavy duty Bilstein shocks which is explained in my write up with pictures
HERE.
Everything I am saying here was done to our rig and it handles very nicely, though ours has the Roadmaster brand stabilizer bars. We did also replace the front steering stabilizer with a heavy duty Safe-T-Plus brand, and added a rear trac bar. You can't go wrong if all you do is install heavy duty front and rear stabilizer bars and heavy duty Bilstein shock absorbers. If you are a decent shade tree mechanic, you can install the bars and shocks yourself. Many forum members have. I would have done so myself back in 2007 had I been educated about all this back then.
Ron Dittmer