Plummer (b. 1947) played in the majors in 1968 and from 1970 to 1978 for the Cubs, Reds and Mariners. He had 168 hits, 14 home runs and a .188 batting average.
He managed the 1992 Mariners to a 64-98 record (.395 win %) during his only stint as a manager.
I mailed to Plummer on November 8 and got the cards back on January 14, for a 67-day TAT.