How long did James MacDonald voice Mickey Mouse?

[Big Disney Fan]

In the summer 1988 issue of Disney News Magazine, there is an article entitled "Mickey's Other Voice", about sound effects man James MacDonald, who, as you probably know, took over the voice of Mickey Mouse in the mid-1940s, during "Mickey and the Beanstalk" (in "Fun and Fancy Free"). MacDonald says that since then, he had been the voice of Mickey for 38 years. The article said that he retired in 1975. That is only about 30 years, not 38. If it had been 38 years like he said, that would mean he wouldn't have retired until about, oh, 1983 or '84 or something. So how long did MacDonald really do Mickey's voice?