I believe the jacket in question is the CWU-36p. It was the “summer” jacket meant to be lighter weight. This is a little more difficult because there are ALOT of jackets that look very similar and to top it off not only does the military change suppliers/vendors all the time but they are also quite a few civilian replicas.
Both of the jackets below were issued (left was issued to an uncle, right was issued to me) and have the exact same nomenclature but obviously look different. I think the one on the left is closer to what you are looking for. The one on the right is flat color wise.
It’s made out of a material that has a slight sheen to The jackets you see in the film appear slightly darker, because they have been weathered. They get darker over time as they pick up oil/fuel/grime etc. If possible I would highly recommend looking for one in person at a surplus store. The pictures from all the various vendors online can be confusing and misleading whether it is intentional or not
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