Yes, you are correct, mine has external cable routers. So your bike is probably a couple of years newer than mine. My fork crown does have the "D" pantograph. My fork crown is the Bocama Pro, I believe, while yours looks like it may be the Bocama Competition (as are the rest of my lugs). Idated the bike from its Shimano components. I have forgotten, but I think it is from 1982 or 1983.

Carl