The model 66 no dash became the 66-1 around 1976-1977. So you may be looking at a 66-1, if that's the correct date you were told. If it IS indeed a 4" no dash, it could have a stainless rear sight, making it more valuable. If the choice were mine, I would take the model 66, even if it is a -1. That is a great price for one, around here that would easily be a $750+ gun all day long. Good luck.