Suffo officially left the club on 5 June 2002, so he was still a Blade when he played for Cameroon against Rep of Ireland on 1 June 2002. The only other United player to play in the World Cup finals was Jostein Flo, all three of Norway's games in USA 94. Nilsen (Norway) and Kelly (RoI) were also in the squads at that World Cup but both didn't make any appearances. Shaun Murphy got close as a Blade to the 02 World Cup finals and played both games for the Aussies v Uruguay in the final play-off games when they dipped out 3-1 on aggregate.
As has been said on this thread already Suffo also won Olympic gold as a Blade at the Sydney Olympics, he also was an African Cup of Nations winner for Cameroon in 2002, scoring one of the pens in the penalty shoot out. David Carney also played for the Aussies in the 2008 China Olympics.