You must call Colt with the serial number to find out.
@1964
1974
You will have to call Colt with the sn to find out.
100-1200 USD or so
100-1500 usd
1970
value depends on overall condition
1000 USD
Post 78 given the sn you provided
Proofhouse.com has sn data.
500-900 uSD
1977.