Whats with the Hueys in the campaign?

They look so anachronistic… like theyre from the 90’s or something instead of the 60’s. Now the devs might have just taken crazy levels of creative liberties, but this is a huge step into the future for these models.

Another explanation could also be that this is all bell’s memories and that of course he wont remember things 100% accurately, another example is i think with the tiger stripey ish jungle camo adler is wearing on his pants and hat in the beginning of fracture jaw… as far as i know, that camo wasnt used in vietnam…

i just dont know, this mystery perplexes me and i just want to know why treyarch chose to use such futuristic seeming hueys for this.

Edit: Huey is the nickname for the UH-1 helicopter

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https://preview.redd.it/2aobkg3krkhc1.jpg?width=3840&format=pjpg&auto=webp&s=f41e378b41d388169ab8bc29ce67e51458771291