Are you asking how to tell the difference between a pre-'64 and a post-'64?
The pre-'64 Model 70 has a Mauser-type three-position safety, controlled round feed, positive extraction, cut checkering, forged steel parts, excellent fit and finish, and is generally a very well-made gun. Then the "quantity over quality" bean counters took over at Winchester, and to save money they dropped the controlled round feed and positive extraction, used stamped parts, changed the slim, graceful stock to a club with pressed checkering and an aluminum trigger guard, and committed other outrages.
I don't claim to be an expert on the matter, but the pre-64 has a Mauser style claw extractor. The post-64 does not, until Winchester reintroduced a modified controlled feed design sometime back in the late '90s if I remember correctly. Also, the older guns will have what is obvious to the eye to be hand cut checkering versus stamped by machine checkering.
Excellent, I've just found an American Rifleman article that shows the difference in the safety lever, and that the "new guns" started with serial # 700,xxx and up.