We install the Tuffy Products under seat lockbox in a 2018 GMC Sierra 1500. This locking steel box offers more than 3,500 cubic inches of storage under key. The lid is split into two halves, which matches the fitment of the rear seat. You can easily open the lid with just one of the seats lifted, from either side of the truck.

The Tuffy Products Under Seat Lockbox sells for about $400.