The numbered set of 1971 Bazooka has twelve more cards over four additional panels than their companion unnumbered set and is often described as a proof, although there's no real evidence to that effect. The set doesn't seem to have seen a retail issue though and is not known in box form, with singles and a handful of panels found.  While not abundant, enough have surfaced over the years that the idea of a "back door" hoard of these originating from a certain dealer or two back in the hazy 70's has some credence. About three times harder to find than the retail issued (unnumbered) set, PSA has graded 13 numbered Clemente's with all but one granted a grade, like this specimen, of Authentic. This example has a too-close cut on the right side but a really crisp image.