I have (or have had) every Bowman, Topps, Bazooka, Dan Dee, and Post Mantle cards. I still have my 1952 Topps....but, this 1969 Mantle (BLUE
background) appears to be "unique".
I acquired this Mantle card back in the 1986. I have searched for another one with this color for 26 years; and, have not seen one.
I'm wondering if anyone else on this forum has seen this Mantle card with the BLUE background ?

.
TED Z