Dick,
Some of the Winchester Custom Shop Model 21s had salt wood. Don Criswell shared with me in a conversation I had with him 7-8 years ago that he personally had seen 5-6 M21s with salt wood, and he had heard about several others. I know of one M21 that had salt wood. Winchester will deny there was ever a problem with their guns, but if it was stocked in the mid-60s I would check the stock for salt. I recommend you take the stock off and verify if you have a problem or not.
Marvin