Welcome to the forums. I haven't seen the x.x format serial number on any Bianchi prior to the 1980s. Typically it's alpha-numeric. Maybe one of those sixes is actually a poorly stamped 'G'? Regardless, it should be from 1986. Please post pictures for confirmation. Ignore the 10 post warning that you will receive from the site. When you upload them, they won't insert in your post but they will be deposited in a gallery album where members can view them.