Don't know if it's the same thing, but I've got what was referred to as a 'single seat unit'? You take the pillion seat and grab rail off, and bolt the unit on. Sorry for being vague, but I'm not sure if it's the same thing as you're after
It's for a black SV640S K4, and is in good condition, with all the fittings and instructions. I'm willing to sell it if you want it (I got it when I bought the bike, but I'll never use it because I always have a tail pack on the bike).
The only snag is that although I'm based in London, it's at my folks house in the midlands and I won't get it down here for a couple of weeks.
PM me if you're interested.
Jo