I sent a e-mail to Hellwig tech support Monday last week and never got a reply.
It looks like to update the rear sway bar on my 2002 i will have to lower the the fuel tank to get to the upper bolt on the left sway bar link it is inside the frame rail right up against the fuel tank. Not sure if it is worth all that work.
I up graded my 2006 f 350 drw 2 wd with helwig front and rear sway bars. The Helwig were much much thicker and made a huge difference. I love how it handles now, and btw I haul a 2002 Lance 1130
I installed a Roadmaster sway bar on my 2015 F350 SRW 4x4 rear, and it made a huge improvement over the much-smaller Ford OEM sway bar. Roadmaster sells the sway-bar and drop-down bars separately, and their sway-bar works with the difficult-to-remove OEM drop-down bars if you already have them.
I have a 2002 F-350 Crew Cab dually 4x4 with a diesel and have both front and rear Hellwig bars and weigh about 12k loaded. They help in corners and make the truck feel more tied together. It was a noticeable difference but not huge. The rear bar is not stiff enough for my liking. I still get rocking pulling out of uneven driveways. Truck Camper Magazine had an article that mentioned just this problem when they had bars installed on their rig. I believe it was Roadmaster they used. They were able to get a slightly thicker bar from another application that made a huge difference for them. I have not taken the time to research larger bars for my truck. I guess I should mention I started with factory bars front and rear before installing Hellwig.
I have front and rear Hellwig on a 95 F-150 2wd regular cab short bed that came from the factory with no bars. MASSIVE improvement and 100% satisfied. Just backing out of the driveway I could feel the difference in stability.