http://armscollectors.com/sn/windates.htm
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your Winchester model 70 was made in 1991.
after 1981
Post 1982
The manufacture date for Winchester Model 70, serial #745481 is 1965.
It is made in 1752
I would place your Winchester model 70 rifles year of production at 1999-2000.
With the serial number that you provided,your Winchester model 70 bolt action rifle was produced in the year 1992.
With the serial number that you have provided,your Winchester model 70 bolt action rifle was made in the year 1988.
With the serial number that you provided,your Winchester model 70 featherweight was produced in the year 1990.
Proofhouse.com has Winchester sn tables.
Go to proofhouse.com.