window sash/ window track, help???

[tre5]

So I have all new parts for the doors, including the doors themselves. I have the new window regulator and new window assembly. My problem is the regulator has rollers where it would attach to the window. The window assembly has bolt holes along the bottom. I'm guessing there is a piece that bolts to the window assembly that the rollers on the regulator slide into. I can't seem to find that piece anywhere though. It would be the track at the bottom of the window that bolts to the window assembly. Anyone know where I can find it? I've tried LMC, Brothers, Classic Truck Parts, and a web search.