dash 2's were made from 1982 thru 1985..../ S&W book doesn't indicate anything more specific.
In this model / on the dash 2's they eliminated the cyclinder counter bore and pinned barrel / but they're still very nice guns. 66's in 4" are all K frame, Square Butt ( if it were a 2 1/2" it would be a round butt). Type of stocks or grips on it - will make a difference.
Grades are :
a. as new in box
b. Excellent
c. Very Good
d. Good...
so Good, is not a great gun...
Most 66's in 4" ...are selling for $ 500 - $ 600 right now in very good to excellent. If it really is "Good" ...then its probably $ 400 or so...