Just an update of sorts. After reading some of the older posts, and having missed one of the threads on his dissappearance, I have been able to link enough info together to give us a clear picture of Hawkeye. I am reasonably certain that this is correct.
Hawkeye once posted on Memorial day that he was a veteran on the 187th Airborne Infantry, 3rd Battalion, Delta Company. I have confirmed that the 187th was organized under the 101st Airborne Assault Division. The 187th are nicknamed the Rakasans, which he also referenced in his post. He described a battle on Hill937 in Vietnam. The history of the 187th details this battle, and mentions specifically an incident in which Delta Company had called in a medevac chopper to evacuate some wounded. As the chopper was loading wounded, it was hit by an RPG and destroyed. This corroborates with Hawkeye's recollection.
William Cashman was a passenger on Flight 93 that crashed in PA. He was a former member of the 101st, which matches. I think most people missed the link between the 187th and the 101st. He would have been the right age as well, and everything else fits. The only thing I have not been able to find is confirmation that William Cashman served in the 187th, but I am reasonably certain that was the case.
Flight 93 - Cashman
As well liked as he was, perhaps we could all donate $1.00 or more for his family or to donate to the September 11 Fund in his name. It would be a small price to pay for all the hot deals he brought to this forum and others.