Yes, there were mid-80's trucks w/w. They are rare...but I've seen a couple. I am not sure how many were built. Maybe, David Doyle will chime in.
One thing I want to point out...it may be obvious to some but not all... I have a 1983 M35A2C. It is not a mid-80s deuce as we refer to them. Why? Because it does not have all of the feautures of the true mid-80s deuces like the dual brake system. So, just because a truck description indicates that a truck was built in 1983 or 1984, does not mean it really is one of the later deuces. It really is no different from a truck built in 1970...just that it was built a few years later. Also, this probably goes without saying, but make sure from the VIN that the truck was not just rebuilt in the 80s.
I hope this helps a little.