Morris Lambert served as Crew Chief beginning October 1970 and on Stallion 038 from April 1971 through July 1971.  The aircraft was painted black with a great "nose art".  A  50 caliber machinegun was mounted on the right side.  A Xeon searchlight and 7.62mm minigun was mounted on the left side.  Awesome firepower for a Huey!!!  
Xeon Searchlight and 7.62mm minigun -  left side
50 caliber machinegun - right side
"Night Mare" nose art
Crew Chief Morris Lambert
Weapons storage for "Night Mare"
A closer look at the minigun
A closer look at "Night Mare"
Stan Edburg
Stallion Platoon Leader

I was the one who arranged to have the mini gun and 50 cal mounted on
the "Nightmare".  Neither I nor my crew named it the Nightmare nor did we paint the nose art, we just called it the night ship. We did however paint it black. I love the name and the artwork. I started flying the night ship as the Aircraft Commander late in my tour, we were assigned to fly night missions each night. After taking fire on most flights I recalled that the Air force had Hueys with mini guns.  One day I visited a helicopter unit at Cam Rahn Bay inquiring about their mini gun setup. 
To my surprise the armorer in charge came from my home town, Spokane WA.  In fact at one time he had lived just a few blocks from where I grew up. I explained that we flew missions at night and were regularly shot at.  I also explained we patrolled the entire Cam Rahn Bay perimeter. He volunteered to install the mini gun and to provide all support and parts for repair, such as barrels motors etc..  None of this was approved or authorized by anyone in  the Army or the Air Force.  Lots of rivets were removed and reinforcement riveted into the floor for the mount, which swiveled inside so the cargo door could be closed.  The ammo chutes were mounted on the back wall.  I flew the aircraft to Cam Rahn for a couple of days.  After the mini gun was installed, an armorer from the 92nd came out to look at the installation.  He suggested he could mount a 50 cal on the other side and I agreed.  Again this was not approved by anyone.  I cannot remember his name, however he was on his 2nd or 3rd tour.  He had survived a nasty helicopter accident as a crew chief, in a former tour and had several 3rd degree burns on his body and arms.  He volunteered to return to Vietnam but was not able to pass a flight physical so could not be back on flight status.  He accepted a job as the armorer.  A great guy,  I wish I could recall his name.
A xenon search light  and  C130 landing lights were also coaxially
mounted on opposite sides.  On the first night test flight we took off looking for a fight.  We did not find one right away and were itching to try things so I gave permission to fire both the 50 cal and the mini gun.  The armorer had also brought an M79 launcher, which he  continually 
reloaded and fired.  Hell, I even fired my 38 pistol.The mini gun sounded like a loud siren, with tracers looking like a laser light.  The interrupter switch had been removed so the barrels got so hot they glowed.  The 50 cal was enormously loud and shook the airframe so badly all the instruments nearly pegged from one side to the other.  I started screaming on the intercom to cease fire because I feared some kind of failure.  It was so loud no one could hear or at least if they could they did not stop until empty.  Pretty awesome to say the least.
Wendle Winston Hadley was the crew chief of 038, he is the one who
painted the entire aircraft black.  Again without any permission or
authorization.  After he painted it and was asked if there would be
trouble his response was "What were they going to do to us?  Send us to Vietnam!!"  That was the attitude back then.  I left and rotated home within a couple of months of configuring this machine and always
wondered what had happened to it.  At the time the commander required us to fly it somewhere whenever a inspection team, battalion commander, or someone inquired about it.
We did get to use it in action a few times and it must of had a bad
reputation, because we could fly around at night with the lights on and
hardly ever get shot at.  In fact one time we were asked to escort a
night medivac into a hot lz.  Every time the medivac tried to land it
took lots of fire.  We turned on all the lights landed in the lz taking
no fire, then left informing the medivac it was ok, they once again took
fire.  We then hovered in the lz while the medivac came in picked up
there patient and then both of us left.  Once again without taking any
fire.  Guess it was too scary??