That’s solid info, thanks! Looks like the OEM rails aren’t “technically” designed for this model. Or the one they have won’t fit my space. I have like maybe 22” until I hit the wall, and most of the rail kits SilverStone has seem to be minimally 22” which wouldn’t account for any rear vent and or power cord space, if it would even fit on my 20” rack.
FWIW I do have the rack lag bolted in 4 spots to a concrete basement foundation.