The model 66 is a nice gun ....K frame ...stainless...they were made in 2 1/2', ( a few 3"), 4", and 6" ....
made from 1970 - 2004...
a no dash - was made between 1970 and 1977..../ no dash and dash 1's are both collectable ..and good shooters.
Value on most model 66's these days ...in excellent condition is $ 500 - $ 700 probably ....its a good entry level S&W revolver / still affordable / and a lot of gun for the money...
here are some of mine ... both 66-1's a 2 1/2" and a 4"
View attachment 79979
-----------------
the older K frame S&W revolvers....model 19's blued or nickel ---demand a little more money ...if they're real clean...very similar guns to the model 66.
Here are some of my model 19's ( a pair of 4" in Nickel at lower right ) ---and a pair of model 66's 4" at upper right (stainless )...
http://thefiringline.com/forums/attachment.php?attachmentid=77426&d=1326326498
--------------------
S&W made revolvers / or makes revolvers ...in J, K , L and N frames for most models ....and they're all collectable...N frames demand a premium ( model 27's in .357 mag / L frame is the model 686 in .357 mag ...) and a lot of variations of all 4 frames...
but most revolver collections / or at least mine ...that comprise 20 or more revolvers...will have a few K frames...( mod 19's and 66's ) ....so hope that helps.