Is there any other way to get the T-51B Power armor besides from

Beside from what?

I know what you are talking about. And YES!...and no. To get a special T-51B armor, you need Operation Anchorage, an Add-on for the game. Since it's not out for PS3 yet, you get either wait to get the add-on, or get it from the fort.

To get it from the fort, you must have done the quest: You Gotta Shoot'em In The Head! For the keys. After you have completed the quest, Follow Mr. Crowley out from the Underworld and into the Train Tunnel (so you don't have a bunch of ghouls killing you when you are about to do this). Once you are in the Train Tunnel....Kill him. Take the keys. Then there is this shack outside of the fort. Go into it and look for a hidden door or a door in the floor. Just trek down into this underground maze until you start finding doors. There should be a safe that is already open. Caps and a Bobblehead (Big Guns) should be there. Get them. Then Continue down until you get to the very end, and there should be a dead raider on the floor, a girl to be specfic. Take her key and go into the locked door in the room. I hope you have some room for the armor.

The one armor in the fort is I think different than the one in the expansion, so get both

Tribal power armour is the best looking besides enclave

It seems the most profitable route that does encounter a glitch but does not break the quest is to:
Get the keys
Talk to Allistair Tenpenny and accept his offer of more money to kill Mister Crowley
Kill Mister Crowley
Return to Allistair Tenpenny for your reward, and ignore the glitch conversation options and map waypoints after you get it
Go to Fort Constantine and get the T-51b Power Armor, which properly ends the quest and grants you the quest experience
TOTAL REWARD: 300 caps+ keys for the T-51b Power Armor

OR (for those who don't mind negative karma)
Shoot Dave, Dukov, and Strayer in the head
Talk to Allistair Tenpenny and do the speech challenge to get 300 caps
Persuade a ghould in underworld to tell you the truth about Mister Crowley
Get 100 caps bonus, 300 caps for the 3 headshots from Crowley (don't mention Tenpenny)
Kill Mister Crowley once he leaves the city and loot all 3 keys
Go back to Tenpenny and get the rest of your pay
TOTAL REWARD: 700 caps+ keys forT-51b Power Armor

wow ive never even seen most of the map were do u learn about that special armor and wht does it do?