And every single year the new recruits were boomers not the silent generation. The silent generation started the war but the boomers are the ones who fought it. The average age was 22 years old. So after year two of the war it's skewed heavily towards boomers
So the ones already in the military would mostly be silent generation going into it and for the first about 5-6 years Silent would have been drafted. Hell it would take three years before Silent Generation was above that 22 years old
At the beginning of the Vietnam war the very first year of boomers would have been old enough to enlist. At the end of the war it was 9 years of nothing but boomers enlisting. with the average age across the decade of war being 22 years old that means the majority of Vietnam veterans are boomers