1976
Impossible to answer without a serial number.
No such weapon made.
about 1971
Made in 1975.
If the serial numbers starts with a "G", you have a Colt Peacemaker Buntline. The serial number you list has to two more numbers than it should have. If the sn is G62260 - it was made in 1973 If the sn is G26028 - it was made in 1971 A New Frontier Buntline would have NF in the serial number.
1-1000 USD depending on exact configuration, overall condition and accessories.
The records I have for Colt single action army, buntline & new frontier AAA (post war) ended in 1978 with # 99999SA. 1979 started with SA01001, so take it from there.
You must call Colt
Proofhouse.com has Colt sn data.
You must call Colt
You must call Colt.