SaxMonkey's insided sources, close to Big George, say that, for the most part, its been Link STM's for most of his career, a "Double Ring" that was used alot in the sixties, and later, various other STM's, most of which were in the 7* to 8 range, with 3 1/2 rico, or rico royals, now 3M Rico Jazz Selects.
For a time in the 1970s to early 80s, he was using a Lawton, I believe an 8. If you look at the YouTube Videos with Cedar Walton in Italy, he's using the Lawton. I believe he even played a Dukoff SuperPowerChamber, for a bit, in the very early 80s, but since about 1984 or so, its been Links all the way.
In the last 4 or 5 years, he's played on a STM with a slight wedge or baffle that he had someone put in for him, most likely for ease of blowing now that he's getting up in years, thats probably what he's playing on the youtube Amad Jamaal video.
And thats all I know.