What's the four digit number under "Spec. Ord."? Starts with a "6" or a "7".
You gun was made in 1986 - 1987. The special order number will help nail it down.
Your gun is a "dash one". Open the cylinder, look at the frame under the barrel, you should see a "Mod. 686-1" there. Above it the s/n. You may also see a "M" there. If not, your gun has not been sent back to S&W for a voluntary recall. Search "recall" for lots of info on that.
A 104223 is a plain standard production 6-inch M686. Forged parts. No lock. With the box, original wood Target Stocks, and in excellent condition, I'd put it in the $650 to $950 range. These fine guns come up all the time here and prices for older ones fluctuate widely around the country.
I'd find out what a brand new 6-inch M686-6 sells for in your area, then set that as the MINIMUM price you'd take. If it were mine, I'd wouldn't sell it for penny less than the new gun with the lock and MIM parts. Upper end is what you can get. Personally, I think they're worth more than the new guns.