There were about 200 SEALs during the entire Viet Nam War. I've met about 650 of them.
Personally, I have been in a position over the last decade and a half or so to give final approval over hires in our company...many of whom were prior service personnel. I get many of our recruiters telling me this guy or that guy was a Seal, Recon, Special Forces or ParaRescue(sp)...only to pull the 214 and find out they were in some admin or rear position assigned to whatever specialized unit they claimed...have to say, Navy Corps-men (as the messiah would say) were the worst at making claims...dunno why.
I know One genuine Navy Seal from the Viet Nam era. He stayed in the Navy and retired. He was an old friend, a better friend to my brother than to me as they were the same age, older than me. He swam in HS, in the LA area and won quite a few ribbons swimming the butterfly.