Gino
I pulled my Grenada (Osprey Men at Arms) reference and can confirm for you the following.
1. Rangers deployed with the M-1 Steel Helmet with Paratroopers harness installed.
2. Rangers were issued the Viet Nam pattern OG-107 (Olive Green Colour 107) Rip Stop Poplin Cotton Uniform and the Helmet Cover was Early Woodland Pattern material.
3. Most wore the Ranger OD green Patrol Cap of course with the "Ranger Crush" to it.
4. 82nd was deployed with Woodland Fatigues and Kevlar PASGT Helmets and Vests
5. Footwear was the Olive Drab Sided Boots Hot Weather (Jungle Boots)
6. Marines, Marine Recon and Navy Seals and Delta were deployed with WOODLAND pattern fatigues.
If you haven't picked figures for this project yet. I would suggest the RANGER's from Dragon or DML along with the SEAL, LRRP or Marine Recon from their 'NAM series of figures Dragon or DML. These will give you an excellent grouping of figures with lots of extras to swap between figures.
The OSPREY Book is also an excellent little reference with lots of good photos and color references for OP Urgent Fury.
If you need any other assistance feel free to reply and/or email me. I'll be happy to help where I can.
Cheers;
Gregory