Rear Window Question

[Houses]

so I picked up a sliding rear window off craigslist. the guy said it was a factory window but I didn't notice the edge of the window where the gasket goes was flat. is this window even from our trucks? do you guys know which gasket will hold it in? the gasket from my solid window didn't work out. I know on other sliding windows they have the flat edge going around the whole window. what do you guys think?