The pickings for good looking and highly functional running boards/steps/sliders for our vans is pretty slim. My guess is that manufacturers don't see a future in providing for vans that are no longer produced so, just when you find something you like, it turns out they don't have a version to fit. There are custom-made ones that cost plenty and may or may not suit the need. There's a guy on here that makes some great sliders (somebody help me out with his handle, I'm blanking...) and they're the real deal for sliding on rocks, but were a little too basic-looking for me. If you want rugged, though, I'd go there. I needed a really good step more than I needed rock protection.
What I really lusted after were the AMP electric steps, but you can't get em anymore. I found a guy in Chicago who adapts the Sprinter version to E350s but wanted something like $3500.
After tons of research, I was about to pull the trigger on the Aluminess nerfs and get a custom powdercoat job (didn't want black). But then I decided to embrace my chrome look for now and found these polished stainless ones, with a nice wide step. At 20% off and free shipping, they were more reasonable. Should be arriving in a few days. I'll let you know how they do.
Luverne MegaStep Nerf Boards - FREE SHIPPING