Quick little guide on how to install the 692981-001 rails. I don't have the support arms for them but those are only necessary for racks that are 29" deep or better. The two screws in the middle are supposed to be there. Ideally you have the original mounting screws with the extra lip. I imagine regular rack screws would work if they have the right threading though.
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https://www.youtube.com/watch?v=lp13bdx7VZQ