It's a little known fact that Warren Spahn rejuvenated his career at the age of 42 in 1963 by adding a knuckleball to his bag of tricks. Spahn went 23-7 for the Milwaukee Braves that year thus matching his career best W-L mark. He posted an ERA of only 2.60 in 33 starts with 22 complete games! The 259 2/3 innings he pitched work out to an average of nearly 8 per game.
Here are scans of my two Warren Spahn cards:
I also have his 1963 Salada Baseball Coin and his 1964 Topps Baseball Coins.