Just go to Ranger Station Delta, at 4pm + and they'll be some walking around for some reason at such low level and rep. Also the one I killed was a ghoul?!?! didn't know ghouls could join NCR let alone be that highly ranked.

Ghouls can indeed join NCR there is at least one outpost that has a few troopers and also a quest in an "irradiated area" that has you dealing with one in-particular if you play a good character (evil you would have shot him dead most likely)

I have been looking for a decent Anti-Material rifle lately

Actually, the ghoul ones were ghoulified after they became NCR Rangers/Troopers (whichever they are). Caesar's Legion attacked the camp and set off a dirty bomb (they call it a radiation bomb, but same concept).

You got the gear from the cover of the game?