Cut off age to enlist is 37, unless you are prior service, then its your age minus years of service, so long as you dont go over 37. Example if you are 40, served 4 years, then you count as being 36 for enlistment.
When I went to basic training in 1984 I was 19, but we had guys that were 23, 24, and one guy was 35. He did it as a change of career. We all looked at him like he had three heads, considering he literally taught chinese at some college in New York. However we later learned he went off to Intel school after doing a breif stint as a MP like the rest of us.
Then when I was in "permannet party" billets, we had a guy who was a E-6 in the reserves, re-enlist active duty. He was 39 at the time, had served in Viet Nam in the early 70's and then was a Baltimore City cop for 10 or 12 years. He too got fed up with the BS of civilian life and went back in as a PFC (E-3). It was funny to see him in Class-A greens, he had more medals (too include a CIB) than any of us, the platoon leader or the company commander. The only person who compared was the platoon sergeant who also had been in Viet Nam. [(:)]
I looked into re-enlisting in the reserves, but I had shoulder surgery 5 years ago, and I was medically disqualified. [:(]