67-72 Chevy/GMC Shortbed Fleetside Bed Floor Assembly For 4" Wider Wheel Tubs. Made to OE specs with the exception of the wheelhouse openings being 4" wider on each side to make the install process painless. This Floor Assembly is stamped from heavy duty 18 gauge metal and has the under bed cross sills already attached with all factory holes pre-punched. Sheet Metal is black coated to prevent rust. 4" wider wheel tubs are available in our store.