Your colt agent was made in 1964.
You need to call Colt
80750D
You can get a letter from Colt.
On a Colt revolver, the serial number is generally in two places. When you open the cylinder you will find the serial number at the base of the frame & crane.
Proofhouse.com has Colt serial number tables.
Colt data at Proofhouse.com
That Colt was made in 1891. Colt started with serial number144000 in 1992.
It is on the frame.
Your Colt Lawman revolver was made in the year 1972.
if your pistol is of the model 1911 with serial number 189558 then it was made in 1917 by colt. If it is the revolver then the serial number is to high for the 1917 revolver.
Proofhouse.com has Colt serial number information you can use.