The 7th Air Cavalry division didn't fly the ARA Huey's.....so thats why you wont see them on any aircav pages. They were flown by the ariel artiliary squadrons that specialised in the flying of the ARA's.
Watching WWS and stating that they were not used in that is, your completely right, showing nothing at all. If you read the book (Which i know is still wrong in some areas but is much much more accurate than the movie) you'll see that the ARA Were instrumental in keep large enemy forces at bay and that the minigun UH-1C's weren't used at all.
If you look for anything on Air Cavalry you wont find much on the ARA.
Consulting a 'battle of the Ia Drang' veterans page i found out this:
"The ARA Helicopters chewing up the slops of the Chu Pong Massif [for those that only know the movie, this was the mountin looming of LZ X-ray] on our behalf were from Charlie BAttery, 2nd Battalion, 20th Artillery (ARA), commanded by Major Roger J. Bartholomew who was also known as the legendary 'Black Bart'....."
So there you are, movies are very rarely factual to specifics. Don't believe anything unless you have many sources confirming that

, thats the first rule or Historical Research.
Vyper