Yes - it's what we called the "composite" box, which is a plastic type material. It was a free flow option for certain model years.
It was actually very cool, as it was durable/ding proof and did not require an aftermarket bed liner. But - they were very expensive (like maybe a $1000 option) and so didn't last very long before the program was killed.
http://www.thetruthaboutcars.com/201...ering-pro-tec/
The composite box was standard on the quad-steer pickups (which didn't help their business case, either).
K