That is his "newer" style.
By that , I mean when he was very young, (say his 1950's - 1960's sigs) he used the capital cursive M's.
You can often see a few of his earlier signed items like this on Ebay, but the vast majority of it is his "newer style", more similar to yours above.
The older style with the capital cursive M's , is a tad bit more sought after. At least that's the way it seems to me, and I watched countless Mick signed stuff on Ebay for several years now.
And as far as your example of his "newer style", it looks damn good to me~!
Just for a comparison, here is a signed index card I picked up within the last 6 months. (This is just a guess, but I'm figuring he signed this index card late '70s - early '80s......judging from the tone and aged look of my index card)
Yep, yours looks good to me. Nice envelope/cover!! Congrats.
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COLLECTING MICKEY MANTLE, ROBERTO CLEMENTE, JACKIE ROBINSON, WILLIE MAYS, HANK AARON and VINTAGE
Successful deals with - "HCV123"/Howard Chasser, "ejstel" , "mzljapan" , "aronbenabe" , "Santo10Fan" , " Robextend", "rjackson44", "Wanaselja", "eliminator", "Dboneesq" , "Oneofthree67", "Lucas00", "ccre" , "D. Bergin" "wawazat", "rugbymarine" and several others.