Stromberg Carlson Tailgate -4000 series.
This strong-as-steel plastic tailgate features a cutout that makes it perfect for towing a 5th-wheel or gooseneck trailer. The locking tailgate has built-in louvers that reduce drag, and it mounts securely with rotary latches and coated cables.

Features:
Convenient cutout for towing a 5th-wheel or gooseneck trailer
Replaces your OEM tailgate during towing or travel to protect it from damage
Glass-filled, black composite plastic frame with louvers
Frame is blow molded to create a lightweight yet strong-as-steel tailgate
Components resist rust
Louvered design reduces drag and improves visibility
Less drag means better gas mileage
Accessory kit (4000-V; sold separately) lets you create a custom look by adding black, paintable steel louvers
Keyed center release mechanism works in conjunction with rotary latches
Locks gate in closed position
Allows for single-handed release
Includes 2 keys
Rotary latches and coated cables secure the tailgate to the truck
Gate lowers to sit flush with truck bed so that you can easily load cargo
Versatile gate can be painted to match truck and accessories

I used it with a 2013 Chev. Silverado and a 2014 GMC Sierra. Lightly used.