Bed extender bracket

I have a gm bed extender from my 2004 Avalanche, I want to install it on a 2007 that I just bought but I don't have the mounting brackets that attached to the bed where the tie down hooks are. I contacted amp research and they told me try the dealer but I can't find a part number for just the brackets and the bed extender is discontinued. Anyone know where I can get the factory gm brackets that came with the bed extender?

I had the same issue.  I posted a wanted thread on here, and luckily found someone who bought a truck that had the brackets and didn't want the extender so I bought them from him.  You might want to try the same.  I don't know of another way other than making your own.