1. From the picture above and from years of watching the show, it seemed like Jack Klugman was older--not by a lot, but older. In fact, Tony Randall was two years older.
2. Yes, I realize that the characters played are not like the actors. But still, can you imagine the show working if the roles were reversed? In fact, Klugman was a lifetime smoker while Randall did not smoke. Yet the slovenly guy who ate what he wanted and smoked, lived 6 years longer.
3. Divorce: On the show, both were famously divorced--which is how they came to be living together. Yet both actors were never divorced and their initial marriages lasted over 50 years. (Klugman did legally seperate from his wife of 21 years, but they never divorced).