Walker (b. 1939) played in the majors from 1957 to 1964 for the Orioles, A's (Kansas City) and Indians. He had a record of 37-44 with 326 strike outs and a 4.36 ERA. He was an All Star in 1959. I instantly regret not looking him up sooner and including his 1991 Crown Orioles card with this TTM request.
I mailed to Walker on December 13 and got the card back on December 22, for a 9-day TAT.