Well, I have tabs on the rails, too. They're seat mounts. The rear of the factory double seat mount on those tabs. Hence my assumption that they were seat mounts. But apples and oranges; there's a lot of differences between our models which make fitting stuff a pain...
My rack, that's supposed to fit my bike, lines up perfectly with those seat mount tabs on the back; it's the front that's the trouble. The rack came with bolts and spacers that slide over the bolts, but I can't make them work in any configuration...
Sorry - I thought you meant my fronts were mounted to the seat mounts. Of course, they're not.
Yes. My fender rails have the same tabs & yes, they would be for the solo pillion seat.
The AVL rack mounts with its front legs on the shock studs. The rack came with very well designed aftermarket shock studs that worked perfectly & that allow the front legs of the rack to be attached with no fuss whatsoever. The OEM shock studs can be put on a shelf somewhere.
The rear legs of the rack then line up perfectly with the tabs that are there for either the dual seat or the rear solo seat.
I don't have a clue about the C5 (although the mounting looks similar) & I see now I should have stayed out of it & ignored the whole subject.