After seeing, and participating in several discussion about just what model of PA you can expect to find at various locations I decided to answer the question once and for all.

I made a totally new character and leveled it up to level 50 via the console before leaving Vault 111 for the first time. I went with level 50 just to be well past the level 28 spot where X-01 power armor is what you will find.

I spent around four hours roaming all over the Commonwealth and here is what I came up with.

Every Power Armor Frame had X-01 modules on it with very few exceptions. The first exception was as expected in the Museum of Freedom. But that did not surprise me at all since Sturges has dialog saying its a T-45 set of PA. The only other exception was Fiddlers Green where I found a set of T-60.

I only checked two locations with NPC enemies at them that also have a set of PA out in the open and not locked in a cage. The Federal Ration Stockpile with Raiders had a set of T-60 on the trailer out front. The other was the Mass Pike Interchange Gunners camp where I found a set of T-60 being worn by the commander of that Gunner base.

Before any one asks, I hit all the Military Road Check points and the normal spots for finding PA. Yes even the barge by the Old North Church, South Boston Military Check point, and the one by Watts Electronics had sets of X-01 PA.

Now, unless the game puts some sets out there randomly, when a new game is started, I think I have answered the question of just what you can expect to find when going out to collect Power Armor. It's all going to be level dependent with the few exceptions I have noted.

I stated all this in that other thread a day or two ago. Ive been running new game+ for 3 characters now, and this is the behavior that has already been confirmed some time ago. And at 50+, you should be seeing Mk III or IV parts on quite a few of the more southern frames.

Leave Vault 111, then Level to 50 and report Your results.

I could do that. I did copy and saved the save files before leveling the character up. What is it your expecting to be different though?

I think the Game Code is affected by Player Level after leaving Vault 101. The partial Suit in the Box on a Railcar just outside Lexington has always been a T-45 regardless of My characters Level. I have a Saved Game where I did avoid most of the Locations and was expecting to find nothing but T-60, and was annoyed by finding large amount of T-51 instead.

The only difference would be that the Sanctuary and Red Rocket cell would be level 1, and then if you leveled to50 before wandering out of Sanctuary, everything else everywhere else would be the same as leaving 111 at 50.

T-45 is great! And T-51 is my favorite.
Interesting, but... what's your point?
That you get T-60 and X-01 at higher levels? I could have told you that.

T-60 is common, I have enough pieces for like six rigs in my container. Boring...
(BoS boring, heheh.)
And X-01 is nasty - it's just fugly. No thanks!

I keep four T-51f rigs, in the beautiful Railroad flat-black paint, inside the Railroad HQ.
One in the rack (my own), and three to keep Des company at her big round table-thing.
It is the T-51 that is flat out gorgeous, and rare, and collectible... is it not?

Yes, but i don't think it matters to me as i only ever needed one suit of power armour at a time.

I gave up equipping companions in full suits.

When they wore it it would just be the frame.

As i progressed through the game i upgraded the power armour I wore, usually finding a few part XO-1's at later stages.

But as I wrote you really only need one.

It would be different if you could be the General of a power armour equipped Minutemen Army but, sadly, you can't. (unless there is a mod)