[3] He graduated from Central Cambria High School in 1957 and played college football at the University of Cincinnati.
[4] Alongside Willie Davis, Henry Jordan, and Lionel Aldridge, Kostelnik was the unheralded member of the Green Bay defensive line.
"[1] In his eight seasons in Green Bay, the Packers won five NFL championships and the first two Super Bowls.
He began working for Mainline Industrial Distributors Inc. of Appleton in sales in the off-season in 1965, became president in 1970,[7][8] and later was its chief executive officer.
[1][9] While returning to Wisconsin from a Florida vacation with his wife Peggy in 1993, Kostelnik suffered a fatal heart attack and lost control of his car on Interstate 75 in Scott County, Kentucky.