So far as I know nobody has decoded the serial numbers for Murray's rebranded bikes - bicycles sold by Sears and Gambles (hiawatha) used a different series of numbers than those sold with the Murray name on them.
But if you know what version of the red band it has you can get a good idea of what year range it was made in. The red band with the splined cog was made 1961-1963, and the red band with the tabbed cog was made 1963-1970 when the "70" came in.