I got a old winchester mod 70 in .270 cal. 3 yrs ago and just took it to a gun smith to clean up and check it out. (SN#522xx). he told me he had never seen this safety on a winchester before. The safety is a thumb safety on the rear tang (moves forward and back like on the Savage rifle) he said it did look factory or someone did a great job in converting it. I was wondering if it is a factory safety ?