It really depends on what you consider a Korean War veteran. If you are talking a veteran of the fighting 1950-1953 (concluding with the Armistice) then yeah, the youngest would be around 80, I would think. On the other hand, since there has never bean a Peace Treaty between the belligerents and combat patrols continue in the DMZ to this day (as far as I know anyway), I guess that means the youngest would probably be 18 or 19.