Around 1931 by proofhouse.com
Colt official police with that serial number was produced in 1927
A Colt official police with that serial number was made in 1948.
Colt official police with serial # 904734 was produced around 1965
1929
Around 1943.
Manufactured in 1950
made about 1958
1959
Made in 1941.
about 1959
Call Colt and they will tell you.
Colt data at Proofhouse.com