I don't believe that is the serial number. The Model 64 is built on the stainless steel K service frame. It is a stainless steel version of the Model 10. Model 64's were first introduced in 1970. It should have a "K" somewhere in the serial number or the serial number will begin with a three letter alpha character.
I don't own a Model 64 so I can't show you a photo of one that includes what the entire revolver looks like.
If it is a dash 3, they were made until 84-85. The pin was deleted some time in 81 and the one the OP has doesn't have a pinned barrel, so it was produced between late 81 and 84-85, when they went to dash 4