At what level does this PA start to appear? I've noticed Plasma gear turning up and I've recently hit level 29, bumped into my first few Deathclaws too, not sure if they're location based etc, but I'm guessing most top gear is level orientated? I read several posts of people saying they've found X01 armor here, and then someone else has found T51b etc.

There is some in fixed locations and some raider bosses use it. I haven't noticed any sort of level requirement for it. Found a set of t-45 in the standard spot and pre lvl 5ish (def pre lvl 10) found a nice suit of t-51

Yeah some of the locations were people said had t-51 only had t-45. One location people had been saying it was fixed at wasnt fixed at all. Now I am a higher level though and i cant go to those spots anymore.... just got to keep on looking i guess