I have several sets of big country wide sider 4" platinum side bars for Silverado Crew Cab and Extended Cab. These are new in the box. Text me at 989-787-2017 if you are interested in a set. This not a cheap knockoff set, it has a very nice finish with welded end caps.

Stainless Steel Finish Features Welded In End Caps
Bolt-On No-Drill Installation For Most Applications
Super Grippy Step Pads For Sure Footing

Asking $175/set.