[skelly423]

Big caveat, I'm not a professional, and am giving a best guess based on very limited experience. That said, here are my thoughts:

Mick only briefly wore number 6 in the early days of his career in 1951, but didn't add the swooping M's to his signature until the late 1950s. The autograph looks good, but the swooping M's and the number 6 just don't belong together. The "O" in NO doesn't look like the O's I've seen in other writing samples. Mickey started his O's at 12:00 and ended at 12:00, this one was started at 10:00 and ended at 8:00

On the balance, I'd say it's probably not legit.