Isn't there also something about an only son not being drafted?
No. I, in fact, was an only child; didn't matter. The "sole surviving son" provision had to do with parents who had other sons die in combat; a final surviving son could be exempted from the draft. I believe it was instituted in WWII.
Some details regarding the draft, from my personal experience: I was drafted in the summer of 1968 (five days before the assassination of Robert Kennedy, in fact, so the memory is pretty specific and vivid). The Vietnam draft lottery was instituted on 1 Desember 1969, so it didn't affect me, as I was already in Vietnam. This was actually
after the peak volume of the draft, which was in 1968.
Prior to the lottery (which was based annually on a person's birthdate), everything was up to your local Draft Board. Every county had one. They were instructed to draft the oldest eligible individuals first, up to the age of 26; but these, and other guidelines were commonly ignored, and there was little oversight from the national Selective Service System of how these boards operated. Lyndon Johnson's Selective Service head was a General Hershey, and he was widely and justifiabl despised, for not just permitting but actively encouraging the squelching of political dissent by drafting those who were known to have protested, and the like.
At the time of the highest draft calls, most men were inducted into the Army, but a minority were inducted into the Marine Corps. An inductee's term of active-duty service was two years. You got pressured toward enlisting for a three-year (or longer) commitment via promises to get certain kinds of specific training; those promises often proved bogus. Once they had you in uniform, they could pretty much do with you what they wanted.
Another matter of gallows humor was the pre-induction physical exam. Again, at the time of the highest draft calls, this was largely a joke. If you had something obviously wrong with you, like being an amputee or blind, you would be dismissed. Beyond that, if you were ambulatory, you generally passed. When I took mine, the technician in charge of checking my heart listened to it for about one second, and wrote down '72' as my resting heart rate. At the time, I was a competitive distance runner, highly fit, and knew that my resting heart rate was something around 50. After being thus passed on the heart test, a few of us compared notes while we were waiting around to pee in a cup or something, and
everybody had a resting heart rate of 72.
Hope this helps.
caw