Hi Greg - there are 5 orders of K48 model bats by Baseball Miscellaneous and not the Red Sox during the 80-83 labeling period. Baseball Miscellaneous usually refers to some promotional type of entity. I do not believe that Yaz used K48 model bats during that time frame. I would be highly skeptical of a K48 bat from this period and provenance would be key. I personally would stay away from K48 Yaz bats from this period. Could he have used this model? Maybe - but use characteristics and provenance would be key to accept one as a legitimate game used bat. If I can be of any further assistance, let me know. Jim