So, to once again beat a dead horse, the car at the Mazda display (Long Road Racing's 1.6L car) at the MSX show had sliders. I asked the gentleman who owns it (I pressume Tom's dad) and he said they are using sparco sliders. I asked if they were FIA sliders and he said they were. So, there you go.
What's very puzzling is that the current rule requires not only that sliders/seat but they must be tested with an FIA Homologated car. So, the sliders themselves don't have to be FIA homologated, the car that they were tested in has to have been. How the heck are we supposed to know that? And if we know that, let's say they were tested in a 911 GT3, how the heck do we prove that to the tech inspectors? Bring in the sample car??? Did someone think through the feasibility of compliance with this rule short of competing in an FIA homologated car? Even then, what's a team with the FIA car to do if they want to change seats out? The new seat wasn't tested with that assembly in the homologation process.
Seats with a back not attached to the main roll hoop or its cross bracing may be mounted on runners only if they were part of the FIA homologated seats assembly specified in an FIA homologated race car.