Chau Co or is it Chau am? Love-Mohinh, I find this post and me talking to you interesting to say the least To start you live in Ho Chi Minh City,a place that when I was there was called Saigon. As you can tell I spent several years in your beautiful county. I am glad there is peace there.

Now to be a bit picky. First your diorama is outstanding. I admire your skill.GREAT JOB!
In the III Corps area Quan loi,An Loc, Tay Ninh ,Song Be You had two units,operating. The 1st Cav Div (airmobile) a division sized unit and the 11ACR (Armored cavalry Regiment( a Brigade sized unit. The 11th Acr was there to support the 1st Cav with armor in case the the enemy(then not now) decided to invade down Hwy 13 (Thunder road) towards An Loc the provincial capital) as they did in the early 70s. But we (the 1st cav were in charge of the AO(area of operations)

Now to be picky. I was did 2 tours in Vietnam with the 1st Cav Div(Airmobile), I was an artillery officer serving with the 1 /21Fa,3rd Bde 1Cav.

The only soldiers that wore the Black Stetson hats were with the 1/9th(1st bn 9cav) ,The divisions Air Cav Troop. Cobras,Gunships and Oh-6. They weren't ground ponders so an officer with the Stetson would be highly unlikely.
the other thing is one of the M 113 is marked with the 11th Armored Cavalry Regt. They shared Quan loi with the 1st Cav but were a distinct separate unit, As far as I can recall/and I am getting older its been 43 yrs/ but the 1st Cav did not have M113s with Gatling guns in the field. We would use/get support from the 11th ACR. Unfortunately Hollywood has blurred reality.( Apocalypse Now).We basically flew then walked.
i can still visualize the rubber traas at Qual loi. Here are some photos of the 3rd brigade Fire base at Quan loi.. Then some of Hwy 13.
My spelling is very bad but I hope this old Dai uy now Dai ta has helped.