Manufactured in 1987. For specific month, you would need to contact Ruger. For another question about it to be answered, you would need to give a specific question.
100-1000 depending on specifics
We can't tell without the serial number- but if you go to the Ruger website, under Customer Service, you can see the year of manufacture for serial numbers. You will need the spefic model of your rifle.
Ruger's website has extensive sn data.
Depending on condition, and WHICH version of the M77, between $250 and $500.
Go to the Ruger website. Under Customer Service, Historical Data, Rifles, M77, and the serial number groups for each year are posted there.
Contact Ruger customer service through the Ruger website. Soem parts will require the rifle be returned to the factory for fitting.
1990
Your Ruger model 77 dates to the year 1983 with the serial number that you have provided.
Around 1981
The Ruger website, under customer service, historical data, rifle, M77, will have the serial number ranges for each year of production.
Ruger's web site has extensive sn data.
Ruger has extensive sn data for their products on their website.