“...I believe it was USAF fast movers, that were instrumental, in saving USMC lives at Khe Sanh, ...”
Mark17 believes in error.
The bulk of close air support for the Khe Sanh garrison was provided by B-52Ds, Es, and Fs.
Yeah, the Buffs were there, but I personally knew F-4 pilots at Mountain Home, who said they also provided close air support to Khe Sanh.
Buffs were fast movers, compared to helicopters. The F-4s were just faster movers. Where I was, we had Vietnamese F-5s and USAF Dragon Flys. I got to fly with them a couple of times. It was quite exciting, especially when they lit the afterburners.