Proofhouse.com has Colt sn data.
If you call Colt with the sn, they will tell you.
That Colt cobra was made in 1976.
check at: proofhouse.com/colt/index.html
Colt data at Proofhouse.com
1965
1965
1970
Proofhouse.com has Colt sn data.
That sn doesn't fall in the Cobra range.
1967
1956
Proofhouse.com has Colt serial numbers you can look up.