Dead Wind Cavern, obtained near the legendary deathclaw. There is a dead Brotherhood of Steel member in a corner wearing the armor. This is also the same area where the unique weapon Mercy is located.
If the player convinces the Brotherhood of Steel to assist the New California Republic in the battle for Hoover Dam, two Brotherhood paladins wearing Brotherhood T-45d power armor will be present during the quest Eureka!
The armor serves as faction armor, allowing the Courier to disguise themselves as a member of the Brotherhood of Steel.
While speaking with Ricky, he may mention that he shot a member of the Brotherhood of Steel through the eyeslit of their helmet. The Courier will respond incredulously, remarking that the eyeslits of T-series power armor are bulletproof.
Brotherhood of Steel paladins rarely wear Brotherhood T-45d power armor. This is because a key list, which indicates it is meant to hold Brotherhood T-45d power armor, is instead composed of Brotherhood T-51b power armor. This also results in armored Brotherhood members occasionally wearing T-51b armor with T-45d power helmets.[verified]
↑Ricky: "I was walking along, minding my own, and up pops one of them Brotherhoods. He yells "Hand over that laser rifle, asshole!" So I hand it over, just to make him think I'm scared! But really I'm not! I never am! Before he knows what hit him, I draw my 11mm machinegun and BAM! BAM! Right through the eyeslit in his helmet! D.O.A.!" Courier: "What a load of crap. The eyeslits of T-series power armor are bullet-proof!" Ricky: "Then I guess this dumb fucker's armor musta been... D-series or something! All I know is, he died up real dead when I killed him, okay?" (Ricky's dialogue)