You can get an idea of the units from their commendations, but you will have to sift through to the bottom where the air units are, from the unit commendations at:

https://lnweb1.manpower.usmc.mil/manpower/mm/mmma/awardsref.nsf/StoredFile/NAVMC+2922/ $File/navmc+2922.htm?OpenElement#viet

I hear that the USMC Historical Center has the Command Chronology of some of the units, declassified ones, here is the address that you have to write to in order to get the information:

Marine Corps Historical Center
1254 Charles Morris Street SE
Washington Navy Yard, DC 20374-5040

or the web site, which is kind of useless for what you want at:

http://hqinet001.hqmc.usmc.mil/HD/Home_Page.htm

Finally,
There are some helo squadrons and squadron veteran associations who have information they can give you that is declassified (i.e. HMM-262 Command Chronology, which we have and our currently putting onto CD ourselves along with our newsletters "Tiger Tales" and other historical data).

I hope this helps, good luck, you might have bitten off more than you can chew with this one. If we can be of any help let us know, we have someone in charge of History for the HMM-262 Vietnam Veterans Association.