The Model 66 was introduced in 1972, the 66-1 was introduced in 1977, the 66-2 was introduced in 1982.
Your Smith and Wesson model 19 was made in the year 1978 by the serial number that you have supplied.
1960
1974
1962-1969
1980
With the serial number that you have supplied,your Smith and Wesson model 66-1 was made in the year 1981.
1969
1982
1974
@1972
75-76
Yes