I was following the posts on the 3" 66 in question and it got me thinking about mine!
I don't have a box and never questioned it's originality. Soooo...I shot an email off to Smith with the serial# and asked oh so nicely if they would tell me how that serial# left the factory. As always got the reply within a day confirming my 66 is an original 3". I suggest the same to settle the issue with this 66. It was free and set my mind at ease.