A good source of Vietnam demographic stats, well annotated is:
(copy & paste.
Indeed, recent studies tend to refute what had been the perceived wisdom of social scientists and other commentators that our V'nam dead came overwhelmingly from the poor communities. An MIT study released in 10-1992 found that our V'nam casualties were only marginally greater from the economically lowest 50% of our communities (31 V'nam deaths per 100000 of population) when compared with the highest 50% (26 deaths per 100000 of population). The class aspects of V'nam service had to do more with the obvious unfairness of sending very young non-college candidates to serve and die while the college bound stayed home. It became particularly reprehensible when the stay-at-homes sometimes became the most visible protesters against the war often vilifying those who were serving and dying.