The armor is found on a dead Brotherhood Initiate inside the Old Olney Sewer, stuck in a culvert with a wastelander and mercenary, also dead. Enter through either of the entrances to the sewer, and make your way to the narrow hallway. The door leading to the room is located on the outward side of the hallway, the entrance is usually guarded by a deathclaw.
The prototype medic power armor has the ability to administer Med-X, which it will do if the player's health drops below 33%, if a limb's health drops below 25%, or if both of these conditions are met Med-X will be dispensed every 2.5 (in-game) hours. Unlike standard Med-X injections, this process carries no risk of addiction. However, it does draw from the player's supply of Med-X, and thus the feature is useless if the player has none. Its outward appearance is nearly identical to T-45d power armor series.
In addition to the Med-X dispensing system, the armor features an on board voice that resembles Mister Gutsy in terms of sound and personality. The voice, similar to a follower, will sound alerts if it detects an enemy presence. Which may help the player notice enemies before the ticks show up on the compass.
As noted in the accompanying manual, the prototype version of the suit lacks the ability to dispense anything other than Med-X, whereas the completed version (which doesn't exist in Fallout 3) would have had a wider range of features, such as deploying stimpaks. The armor was planned as an automatic medical supply dispenser, meaning troops would not have to be evacuated for medical treatment. The user manual found with the armor details that the final version was to also include a lethal chemical that would trigger if the soldier deserted.
Med-X administered by the suit is registered differently from Med-X that is administered normally. If you look at the effects page in your Pip-Boy 3000, it will read "suit Med-X - Ignore Neg Eff +1, Dam. Res. +25." The extra effect of the suit's Med-X ("ignore neg eff +1") negates the effects of crippled limbs (i.e. if you get a crippled leg, the suit's Med-X will prevent you from limping). You can also co-administer Med-X the normal way, which will be listed separately (but concurrently) as "Med-X - dam. res. +25," This allows one to receive a total of +50 damage resistance from Med-X.
This armor has the U.S. Armed Forces insignia instead of the Brotherhood of Steel's, like normal power armor.
This armor can be very helpful in battle as it will always shout out phrases such as "Let 'em eat lead!" to alert you of danger. In some cases, its Perception may be better than your own, and it can spot enemies coming from any direction.
The suit's speech can give away your position to hostile creatures.
Even though the user manual for the armor asserts that "even a child could use it," the player still requires Power Armor Training to use it.
This armor remains in the Fallout: New Vegas game files, but the scripts and sounds are not properly implemented.
The following is based on Fallout 3 cut content and has not been confirmed by canon sources.
In the room that contains the T-51b power armor at Fort Constantine the terminal to unlock the stasis field and retrieve the armor says "Medical Armor Prototype" hinting that the Prototype medic power armor was to originally be held in Fort Constantine.
End of information based on Fallout 3 cut content.