This so-called Heuer AMI protoype has been discussed in an Italian forum before https://orologi.forumfree.it/?t=73524668 It was successfully auctioned in 2017 https://www.liveauctioneers.com/en-gb/item/50127528_heuer-ami-chronograph-switzerland-1980s Just recently it has been listed on Chrono24 and ebay by a Dutch dealer. You can still see it on ebay if you search for Heuer Prototype in Completed Listings. The item number is 163833410805. I almost bought it! The dealer said he's fed up with being offered 2000-3000 euros so he's removed it from Chrono24 and ebay and sent it to Christie's. I would love it to be genuine - it's my ideal watch. But I suppose if it was genuine it would probably be worth a fortune.