Based on proofhouse.com the 1977 colt cobras shows serial numbers 60001R - 71400R & 1978 as just 63401R????????
Your colt cobra was made in 1966.
colt cobra 38 special serial number 139350
1967
Early 1969.
Proofhouse.com has Colt sn data.
1974
Impossible to answer without the serial number.
1969/1970
Proofhouse.com has Colt sn data.
Can't be answered without the serial number. You need to call Colt.
Don't know the value, but Serial numbers B83551 - B99999 were made in 1972.