Proofhouse.com has Colt sn tables. You can also call Colt and they will tell you.
Post 78
made about 1977
Around 1968.
You will have to call Colt. Published sn data does not show any Diamondback with a sn starting with a P
are you sure the '0' is not a 'D' ????? in the serial number
Without serial number, between 1966 & 1988.
You will have to call Colt.
Proofhouse.com
what is the manufacturing date fo a colt diamondback serial number O72239
1972
Go to : www.proofhouse.com
made 1976