Yamaha NS-690 II Speakers?? Help Identify

I recently purchased a really nice pair of Yamaha speakers at an estate sale that needed refoaming. After fixing them, I hooked them up and can't believe that they sound this good. The cabinets are overbuilt and they are very heavy. Look almost identical to the NS 1000. Does anyone know anything about these? They must be high end. What was the original retail? I have never seen another pair. Thanks all.