I'm now a one-bike garage, so time to unload extra accessories.
This handlebar mount works for zumo 660 & 665, and I believe the BMW Navigator IV. Part # 010-11270-03
I bought this new and never opened it. Undisturbed factory packaging as shown in photo below. Includes RAM ball mount.
These are discontinued and selling for crazy prices on eBay, as you can see in this screen shot of completed auctions.
Yours for $180 w/ free US48 shipping. Paypal, check... whatever.