The third is to the north, near an old bridge.
5 seconds sound clip from the The Green Berets (1968) movie soundboard.
You can hear this line at 00:35:12 in the Blu-ray version of the movie.
Quote context
[...]
- Yes, sir, I know. Tell Petersen. Tell the scrounger. Petersen!
- What happens if Charlie hits this camp before you get it completed?
- One is by that shale cliff you saw on your way in.
- The third is to the north, near an old bridge.
- What if Charlie overruns the camp?
- Commander of this area runs everything by the book. And I am with him to the nth degree.
[...]