Alan is being too kind. I know a wee bit about Chiefs but not all J-frames.
I don't find ship dates in the database for any Chiefs with a 549xxx
serial number, but one standout feature among the ones I do list
is the stocks. None near 549xxx have diamond stocks, which tells
me if the serial number on the right stock of yours matches the gun
and does not have a diamond around the nut escutcheon, it
likely shipped in 1968, the first year we've seen Chiefs without
the diamonds. Those stocks are unusual, too, because they have
the same large checking pattern as the diamond stocks. The
next style with a shorter, narrower checking pattern began
between late 1968 and early 1969.