Looking for info on aftermarket cab extender for pickup truck?

I was given an aftermarket cab extender for a pickup truck. It is a fiberglass extension for the cab of a pickup truck. It Adds two seats. You remove the window of the truck and it fits against the back wall there is a door in the bed of the truck and windows. It is VERY cool. But it needs a new seal. I have been looking for hours and cant find who sells these things. The only logo on it says cab extender. Does anyone know anything about them? There is one for sale on EBAY but he list NO information about his.