100-1000 USD or so
Your winchester model 70XTR was made by winchester in 1983.
I would say between 1987-1989,with the description and serial number that you have provided.
Impossible to answer without a serial number. Even then, the data might not exist.
Go to Proofhouse.com and look at the Winchester sn data.
your winchester model 70xtr was made by winchester in 1984.