chadintex:
Your Model 13-2 .357 Magnum Military & Police Heavy Barrel was manufactured between 1977 & 1982. The serial number should fall in the range 2D0001 to 17D8900. The number you are quoting is probably an assembly number, used to track parts in the factory. The serial number will be found on the bottom of the grip frame. You may need to remove the grips to see it.
Post the number and I'll give you a year.
rikman:
Your Model 57 .41 Magnum Target was manufactured in 1979 or 1980, the N6xxxxxx range spanned those years. As your number is high in that range I would guesstimate 1980.
newfalguy101:
Your Model 29-3 .44 Magum was manufactured in 1983.
breeze010:
Your Model 10-5 .38 Military & Police tapered barrel was manufactured in 1969 or 1970. Serial range for those years was D90001 to D330000, so 1970 seems pretty certain.