Craig, the bike looks great! As I am sure you have realized by this point the 85's had the second "semi tubular" rear fork. I am not looking at serial numbers at this point but I would suspect that bike is 1883. 83 and 84 are hard to differentiate but 82-84 had the first style (and I think oft broken) rear fork. The only difference between 83 and 84 that I can think of off the top of my head is the rear spring seat "clamp" for lack of a better word, for the rear of the seat spring that is screwed to the backbone. the 83's were a plain forging, the 84 had the anti rattle style with a screw in it. I think that doesn't apply here with the optional swing spring, but I would suspect Columbia put out at least 3000 experts the first two years as they sold 1079 of the primitive standards the first two years of that model.