Granted my experience is really only with the CF, but from my understanding if you want "Thunder Run" uniforms, you're more likely to see USMC in Woodland MOPP suits, and ARMY in 3 Colour desert. ACU/UCP didn't turn up until 2006-7, and Multicam was only in Afghanistan for a long time, and even then, post 2010. Also worth keeping in mind, as you do your research, ACU is not a camouflage, but a uniform style/format/system.
As to the M203, there should really be one per fireteam for Army, I'm not sure about USMC. You will also see much more regimented gear in the Marines, but army guys may be using their issue IOTV w/Molle pouches, or chest rigs over top, LBVs etc..there's alot of variety out there.
Hope this helps keep things clear as mud for you....