This is just my 2 cents as I'm no Air Force Huey expert. I assume you want to build an armed bird, correct? Page 42 has photos of two different setups. the top bird is a slick for inserting troops and has an M60D doorgun on an M23 mount it looks like. The bottom photo shows a UH-1N gunship with 7 shot rocket pods and, I believe, M134 miniguns on the XM93 system in the cabin. Which are you building? As for the interior, this was pre-NVG so the inside should be grey like every other Huey of the time period as far as I know. The seats would be the same as typical armored Huey seats found on Army birds. The major difference up front would be the instruments which are much busier on a twin engine bird than on a single engine one like the UH-1H. If you are building the slick, seating arrangement in the Uh-1N is basically identical to a H model. Which is to say that seats can be arranged MANY different ways depending on the mission. My GUESS, and please someone correct me if I'm wrong, is that the gunship only had the 2 seats in back gunners position for the gunner and crew chief with teh guns mounted as they are on the VNAF bird I posted earlier. What I don't know is how they were arranged. Without some real evidence, you are just gonna have to guess based on the UH-1P pics I think. My guess is that there aren't many good pics of the interior or Mutza would have found them. Lacking all other resources, I would use the VNAF bird I posted above as a guide for the interior as the cabin is essentially the same. Good luck! if I find anything better, I'll post em for you.
Ray
PS: Not sure if it will help much, but here is a walkaround I did a while back of a current N model fresh from the Gulf. At least you can get a peek inside an N model.
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