Published sn data does not cover it. You will have to call Colt.
@ 1978
Try proofhouse.com.
Call Colt and they will tell you.
70 series ,about $700 max
Sn goes beyond published references. You will have to call Colt to find out.
That Colt model 1911 was a commercial model, not a government model and based on the serial number, it was made in 1947.
Model 1911 commercial .45 with serial number 287589C was made in 1960. It was not a government issue.
I believe 1986. I have a "rc" I bought new in '86.
The government model with that serial number was made by Colt in 1944.
For Colt series,try www.proofhouse.com
Colt model 1911 .45 commercial with that serial number was made about 1966.
A Colt government model .45 with that serial number was made in 1917.