I had never heard of the 3615 until this thread, but I looked it up in Patrizzi's reference book and there it is. It is a minute repeater, chronograph, perpetual calendar and moon phase with a small sweep seconds hand nonetheless! The book says it was made in 1986 and is apparently in the PP museum.
It would be interesting to know why they never made any more. Perhaps they couldn't get it to work?
Steve