As Tom notes, if it has the full underlug it's almost certainly a 686, if it doesn't it's a 66.
If it has 7 chambers, it's a 686+. If it has 6 it could be either a 686 or a 66.
The 66 was built on the smaller K-Frame, the 686 on the larger L-Frame.
On my screen your very poor photo appears to POSSIBLY have 7 chambers, but I can't tell for sure. I count 6 brass, but it looks like there may be room enough on the far side of the cylinder for an empty chamber.
If it does & it has the full underlug it's NOT a 66.
You do know where the model's stamped on the guns, right?