Here's the low down on 80/20 CAD files - at least in terms of fasteners. I found their CAD resources page. They have no fractional models available - but they have 420 models for metric
I called to ask them and what I write is correct at least according to the person I spoke with. I downloaded the catalog. It is all fractional with no metric. Seems strange but, oh well. As a CAD mooch, I really can't complain
